* Sectarian killings emerge as growing threat to Pakistan's stability
* Reuters examines new cycle of tit-for-tat murders in Karachi
* Radical Islamist calls for boycott of Shi'ite minority
* Small Shi'ite force hunts clerics in retaliatory attacks
When Aurangzeb Farooqi survived an attempt on his life that left six of his bodyguards dead and a six-inch bullet wound in his thigh, the Pakistani cleric lost little time in turning the narrow escape to his advantage.
Recovering in hospital after the ambush on his convoy in Karachi, Pakistan's commercial capital, the radical Sunni Muslim ideologue was composed enough to exhort his followers to close ranks against the city's Shi'ites.
"Enemies should listen to this: my task now is Sunni awakening," Farooqi said in remarks captured on video shortly after a dozen gunmen opened fire on his double-cabin pick-up truck on Dec. 25.
"I will make Sunnis so powerful against Shi'ites that no Sunni will even want to shake hands with a Shi'ite," he said, propped up in bed on emergency-room pillows. "They will die their own deaths, we won't have to kill them."
Such is the kind of speech that chills members of Pakistan's Shi'ite minority, braced for a new chapter of persecution following a series of bombings that have killed almost 200 people in the city of Quetta since the beginning of the year.
While the Quetta carnage grabbed world attention, a Reuters inquiry into a lesser known spate of murders in Karachi, a much bigger conurbation, suggests the violence is taking on a volatile new dimension as a small number of Shi'ites fight back.
Pakistan's Western allies have traditionally been fixated on the challenge posed to the brittle, nuclear-armed state by Taliban militants battling the army in the bleakly spectacular highlands on the Afghan frontier.
But a cycle of tit-for-tat killings on the streets of Karachi points to a new type of threat: a campaign by Lashkar-e-Jhangvi (LeJ) and allied Pakistani anti-Shi'ite groups to rip open sectarian fault-lines in the city of 18 million people.
Police suspect LeJ, which claimed responsibility for the Quetta blasts, and its sympathisers may also be the driving force behind the murder of more than 80 Shi'ites in Karachi in the past six months, including doctors, bankers and teachers.
In turn, a number of hardline Sunni clerics who share Farooqi's suspicion of the Shi'ite sect have been killed in drive-by shootings or barely survived apparent revenge attacks. Dozens of Farooqi's followers have also been shot dead.
Discerning the motives for any one killing is murky work in Karachi, where multiple armed factions are locked in a perpetual all-against-all turf war, but detectives suspect an emerging Shi'ite group known as the Mehdi Force is behind some of the attacks on Farooqi's men.
While beleaguered secularists and their Western friends hope Pakistan will mature into a more confident democracy at general elections due in May, the spiral of killings in Karachi, a microcosm of the country's diversity, suggests the polarising forces of intolerance are gaining ground.
"The divide is getting much bigger between Shia and Sunni. You have to pick sides now," said Sundus Rasheed, who works at a radio station in Karachi. "I've never experienced this much hatred in Pakistan."
Once the proud wearer of a silver Shi'ite amulet her mother gave her to hang around her neck, Rasheed now tucks away the charm, fearing it might serve not as protection, but mark her as a target.
Fully recovered from the assassination attempt, Farooqi can be found in the cramped upstairs office of an Islamic seminary tucked in a side-street in Karachi's gritty Landhi neighbourhood, an industrial zone in the east of the city.
On a rooftop shielded by a corrugated iron canopy, dozens of boys wearing skull caps sit cross-legged on prayer mats, imbibing a strict version of the Deobandi school of Sunni Islam that inspires both Farooqi and the foot-soldiers of LeJ.
"We say Shias are infidels. We say this on the basis of reason and arguments," Farooqi, a wiry, intense man with a wispy beard and cascade of shoulder-length curls, told Reuters. "I want to be called to the Supreme Court so that I can prove using their own books that they are not Muslims."
Farooqi, who cradled bejewelled prayer beads as he spoke, is the Karachi head of a Deobandi organisation called Ahle Sunnat wal Jama'at. That is the new name for Sipah-e-Sahaba Pakistan, a forerunner banned in 2002 in a wider crackdown on militancy by Pakistan's then army ruler, General Pervez Musharraf.
Farooqi says he opposes violence and denies any link to LeJ, but security officials believe his supporters are broadly aligned with the heavily armed group, whose leaders deem murdering Shi'ites an act of piety.
In the past year, LeJ has prosecuted its campaign with renewed gusto, emboldened by the release of Malik Ishaq, one of its founders, who was freed after spending 14 years in jail in July, 2011. Often pictured wearing a celebratory garland of pink flowers, Ishaq has since appeared at gatherings of supporters in Karachi and other cities.
In diverse corners of Pakistan, LeJ's cadres have bombed targets from mosques to snooker halls; yanked passengers off buses and shot them, and posted a video of themselves beheading a pair of trussed-up captives with a knife.
Nobody knows exactly how many Shi'ites there are in Pakistan -- estimates ranging from four to 20 percent of the population of 180 million underscore the uncertainty. What is clear is that they are dying faster than ever. At least 400 were killed last year, many from the ethnic Hazara minority in Quetta, according to Human Rights Watch, and some say the figure is far higher.
Pakistani officials suspect regional powers are stoking the fire, with donors in Saudi Arabia and other Sunni-dominated Gulf countries funding LeJ, while Shi'ite organisations turn to Iran.
Whatever factors are driving the violence, the state's ambivalent response has raised questions over the degree of tolerance for LeJ by elements in the security establishment, which has a long history of nurturing Deobandi proxies.
Under pressure in the wake of the Quetta bombings, police arrested Ishaq at his home in the eastern Punjab province on Friday under a colonial-era public order law.
But in Karachi, Farooqi and his thousands of followers project a new aura of confidence. Crowds of angry men chant "Shia infidel! Shia infidel" at rallies and burn effigies while clerics pour scorn on the sect from mosque loudspeakers after Friday prayers. A rash of graffiti hails Farooqi as a saviour.
Over glasses of milky tea, he explained that his goal was to convince the government to declare Shi'ites non-Muslims, as it did to the Ahmadiyya sect in 1974, as a first step towards ostracizing the community and banning a number of their books.
"When someone is socially boycotted, he becomes disappointed and isolated. He realises that his beliefs are not right, that people hate him," Farooqi said. "What I'm saying is that killing them is not the solution. Let's talk, let's debate and convince people that they are wrong."
Not far from Farooqi's seminary, in the winding lanes of the rough-and-tumble Malir quarter, Shi'ite leaders are kindling an awakening of their own.
A gleaming metallic chandelier dangles from the mirrored archway of a half-completed mosque rising near the modest offices of Majlis Wahdat-e-Muslemeen - known as MWM - a vocal Shi'ite party that has emerged to challenge Farooqi's ascent.
In an upstairs room, Ejaz Hussain Bahashti, an MWM leader clad in a white turban and black cloak, exhorts a gaggle of women activists to persuade their neighbours to join the cause.
Seated beneath a portrait of Ayatollah Khomeini, the Shi'ite cleric who led the 1979 Iranian revolution, Bahashti said his organisation would not succumb to what he sees as a plan by LeJ to provoke sectarian conflict.
"In our sect, if we are being killed we are not supposed to carry out reprisal attacks," he told Reuters. "If we decided to take up arms, then no part of the country would be spared from terrorism - but it's forbidden."
The MWM played a big role in sit-ins that paralysed parts of Karachi and dozens of other towns to protest against the Quetta bombings - the biggest Shi'ite demonstrations in years. But police suspect that some in the sect have chosen a less peaceful path.
Detectives believe the small Shi'ite Mehdi Force group, comprised of about 20 active members in Karachi, is behind several of the attacks on Deobandi clerics and their followers.
The underground network is led by a hardened militant codenamed "Shaheed", or martyr, who recruits eager but unseasoned middle-class volunteers who compensate for their lack of numbers by stalking high-profile targets.
"They don't have a background in terrorism, but after the Shia killings started they joined the group and they tried to settle the score," said Superintendent of Police Raja Umar Khattab. "They kill clerics."
In November, suspected Mehdi Force gunmen opened fire at a tea shop near the Ahsan-ul-Uloom seminary, where Farooqi has a following, killing six students. A scholar from the madrasa was shot dead the next month, another student killed in January.
"It was definitely a reaction, Shias have never gone on the offensive on their own," said Deputy Inspector-General Shahid Hayat.
According to the Citizens-Police Liaison Committee, a Karachi residents' group, some 68 members of Farooqi's Ahle Sunnat wal Jama'at and 85 Shi'ites were killed in the city from early September to Feb. 19.
Police caution that it can be difficult to discern who is killing who in a vast metropolis where an array of political factions and gangs are vying for influence. A suspect has yet to be named, for example, in the slaying of two Deobandi clerics and a student in January whose killer was caught on CCTV firing at point blank range then fleeing on a motorbike.
Some in Karachi question whether well-connected Shi'ites within the city's dominant political party, the Muttahida Quami Movement, which commands a formidable force of gunmen, may have had a hand in some of the more sophisticated attacks, or whether rival Sunni factions may also be involved.
Despite the growing body count, Karachi can still draw on a store of tolerance. Some Sunnis made a point of attending the Shi'ite protests - a reminder that Farooqi's adherents are themselves a minority. Yet as Karachi's murder rate sets new records, the dynamics that have kept the city's conflicts within limits are being tested.
In the headquarters of an ambulance service founded by Abdul Sattar Edhi, once nominated for a Nobel Prize for devoting his life to Karachi's poor, controllers are busier than ever despatching crews to ferry shooting victims to the morgue.
"The best religion of all is humanity," said Edhi, who is in his 80s, surveying the chaotic parade of street life from a chair on the pavement outside. "If religion doesn't have humanity, then it is useless."