* Pope urges Christians to counter "grim trail of death"
* Hezbollah politicians among attendees at seafront Mass
* Faithful glad pope visited region, say he encourages them
Pope Benedict urged Arab leaders on Sunday at a huge open-air mass in Lebanon to work for reconciliation in a Middle East riven by Syria's civil war and blazing with fury over a film mocking the Muslim Prophet Mohammad.
"May God grant to your country, to Syria and to the Middle East, the gift of peaceful hearts, the silencing of weapons and the cessation of all violence," the pope said in a prayer after a mass that organisers said was attended by 350,000 people.
Activists say more than 27,000 people have been killed in Syria's 18-month-old, mainly Sunni Muslim uprising against President Bashar al-Assad, who belongs to the minority Alawite sect that grew out of Shi'ite Islam.
Few of the Christians who form about 10 percent of Syria's population have joined the uprising. Some fear it could bring hostile Islamists to power in a fight raging just 50 km (30 miles) east of Beirut.
Addressing worshippers on the Mediterranean seafront, close to the front line of Lebanon's 1975-1990 civil war, Benedict said Lebanese people "know all too well the tragedy of conflict and ... the cry of the widow and the orphan".
"I appeal to the Arab countries that, as brothers, they might propose workable solutions respecting the dignity, the rights and the religion of every human person," the 85-year-old pontiff said.
Peace between warring factions and among the many religious groups in the Middle East has been a central theme of his visit to Lebanon, along with his call to Christians not to leave the region despite war and growing pressure from radical Islamists.
"In a world where violence constantly leaves behind its grim trail of death and destruction, to serve justice and peace is urgently necessary," Benedict said.
NO FILM REFERENCE
The pope has made no reference during his three-day visit to a film made in California depicting the Prophet Mohammad which has caused unrest across the Muslim world, including a protest in north Lebanon on Friday in which one person was killed.
He left for Rome late on Sunday from Beirut's seaside airport. At the departure ceremony, Benedict especially thanked the Muslim leaders who attended his events and shook hands warmly with four of them among officials wishing him farewell.
"I was able to see, during all my visit, how much your presence contributed to the success of my voyage," he said. "The Arab world and the whole world will have seen Christians and Muslims united in this troubled time to celebrate peace."
Politicians from all sectors of multi-faith Lebanon attended the mass, including from the militant Shi'ite group Hezbollah. Leaders of the country's main religions all assured the Vatican of their support for the visit in advance.
The mass took place next to the port without any shade for the crowd, despite temperatures of more than 30 degrees Celsius (86 Fahrenheit). The altar was shielded under a canopy, but the pope was seen mopping sweat from his forehead. Red Cross workers carried away at least two worshippers who fainted from the heat.
Cedars of Lebanon, the country's symbol, featured in a white backdrop to the altar where the pope presided over the mass, and on the white capes worn by prelates of the Maronite Church, the largest of six Christian churches there linked to the Vatican.
Prelates from other Eastern Catholic churches stood out in their distinctive gold or black vestments, in contrast to the green chasuble worn by the pope. Hymns in Arabic added a local touch to the Gregorian and classic Catholic works being sung.
Streets near Beirut's port were closed to traffic in the morning and soldiers manned main intersections. Three military helicopters buzzed overhead and a navy ship patrolled offshore.
Worshippers at the mass were grateful the pope came to Lebanon, where Christians make up about a third of the population. Their community is split into a dozen churches and the Muslims into Sunnis, Shi'ites and Alawites, as well as the Druze whose traditions mix Shi'ism and other influences.
Eli Baalina, 17, a Lebanese Maronite, said the visit "came at a perfect time, when things were heating up a bit".
"It's a good chance to reflect on the things like sectarianism and extremism, things that we all need to work to change about ourselves in this region," he said.
Several in the crowd were heartened by the pope's repeated calls for Christians to stay in the Middle East, where war, emigration and discrimination have cut their ranks to 5 percent of the population now compared to 20 percent a century ago.
"His message is to give us pride and encouragement that it is worth the effort to work for coexistence and understanding," said Maronite Silva Mansour.