Russian authorities said they detained five suspects on Friday over attacks that wounded the top Islamic official in the mostly Muslim Tatarstan region, killed his deputy and raised fears of the spread of militancy to Russia's heartland.
President Vladimir Putin and top security officials called at the weekly meeting of his Security Council for tough measures against extremism after the attacks in an area previously held up as a model of religious tolerance.
Participants underscored the need to "step up opposition to all forms of extremism, including religious," state-run news agency RIA quoted Putin's spokesman Dmitry Peskov as saying.
The federal Investigative Committee suggested the attacks were provoked by disputes over faith and money.
Tatarstan's mufti, Ildis Faizov, was rushed to hospital after three powerful blasts hit his car in Tatarstan's capital, Kazan, on Thursday. A little earlier, deputy mufti Valiulla Yakupov was shot dead outside his home.
The attacks evoked the deadly violence that plagues mainly Muslim regions of the North Caucasus, where Russian forces have fought rebels in two devastating wars since the 1991 Soviet collapse and militants want to carve out an Islamic state.
Oil-producing Tatarstan, which has a higher degree of autonomy from Moscow than most regions and has a majority ethnic Tatar population, is relatively peaceful. Its historic capital Kazan, on the Volga River, has been chosen as the host city for the World University Games next year.
"Investigators believe the main motive was the professional activity of the victims, including their ideological differences with opponents," investigators said in a statement.
Faizov had taken "a tough position toward organizations that preach radical forms of Islam", they said.
"In addition, he took control of the movement of financial resources of the organization Ideal-Hadzh, which sent Muslims to Mecca, and on this basis a conflict occurred between the mufti and the leader of this organization, which threatened him."
It said the chairman of Ideal-Hadzh, Rustem Gataullin, 57, was among those detained, along with the leader of a Muslim place of worship, Murat Galleyev, an Uzbek citizen and two other residents of Tatarstan.
Putin, who has emphasized the need for religious tolerance and unity in a mainly Orthodox Christian country with a large Muslim minority, promised on Thursday that the culprits would be found and punished.
"It is a serious signal," Putin said of the attacks, carried out hours before the Muslim holy month of Ramadan began at sundown on Thursday.
'ISLAND OF STABILITY'
Corruption and suspicions of vote fraud - the same problems that stoked the biggest street protests of Putin's 12-year rule in recent months - are helping fuel the spread of conservative Islam in Russia's Muslim regions.
Many young people are attracted to Salafism, a puritanical branch of Islam.
Analysts say Faizov, elected as mufti in April 2011, has cracked down on non-traditional clerics, some of them natives of the North Caucasus, and local authorities believe some clerics are spreading extremist ideology.
Dozens of alleged members of Hizb ut-Tahrir (Islamic Party of Liberation), a group banned in Russia since 2003 but allowed to operate in the United States and most European Union countries, have been arrested in recent years.
Tatarstan President Rustam Minnikhanov vowed late on Thursday to stamp out extremism in the region.
"I promise that the toughest measures will be taken," he said on the region's website. "Tatarstan has always preached traditional Islam and will continue to do so in the future."
"You can't isolate the Caucasus and say everything bad happens there and nowhere else. This is a single country with common problems," said Akhmet Yarlikapov, an expert on Islam with the Russian Academy of Sciences.
"There are many ... who want to destabilize the situation in the region because Kazan has really been an island of stability for a long time among the Muslim regions in Russia."
Others doubted whether militant ideology was behind the attacks. "Any terrorist attack is easy to attribute to extremists, but I think this is a prosaic problem," sociologist Enver Kisiriyev, an expert on the North Caucasus at the Russian Academy of Sciences, told Reuters.
"The true concern of the political and any other elite in Russia today is money."