DAMASCUS // World leaders voiced shared fears on Friday that Syria stands on the brink of all-out civil war but found little agreement on how to bring it back from the abyss.
Talks in Berlin between German Chancellor Angela Merkel and Russian President Vladimir Putin exposed the sharp differences between Arab and Western governments and Damascus allies Beijing and Moscow on the way forward.
The two leaders found common ground on backing the peace mission of UN-Arab League envoy Kofi Annan but the former UN chief himself admitted to frustration at the slow progress he was making in staunching the bloodshed, as human rights monitors reported another 15 people dead.
Security forces opened fire on demonstrators in several towns as protests were held across the country against the killing of 108 people, most of them women and children, near the central town of Houla last week, activists said.
UN human rights chief Navi Pillay said that the killings -- which UN officials have said were the result of army shelling followed by a ground assault by loyalist militia -- could constitute a "crime against humanity."
An inquiry by the Syrian government blamed rebel fighters but Washington dismissed its finding as a "blatant lie."
After his talks in Berlin, the Russian president acknowledged that Syria could be teetering on the edge of civil war but underlined his opposition to military intervention to stop the bloodshed.
"You cannot do anything by force," Putin told reporters.
He hit back at suggestions Moscow was supplying arms for use in Syria, saying his country did not deliver weapons to be deployed in civil conflicts.
"As far as arms supplies are concerned, Russia does not supply the weapons that could be used in a civil conflict," he said.
The president, on his first trip to the West since returning to the Kremlin for a third term, insisted his country was not siding with President Bashar al-Assad's regime against the opposition.
"We are supporting neither side from which the danger of civil war is coming," he said.
Merkel said the two leaders had agreed on the importance of backing Annan's peace mission.
"We both made clear that we are pushing for a political solution, that the Annan plan can be a starting point but that everything must be done in the United Nations Security Council to implement this plan," she said.
But speaking in Syrian neighbour, Lebanon, on Friday, Annan spoke of his frustration at the slow progress in implementing his six-point peace plan that was supposed to begin with a ceasefire from April 12 but which has been violated daily.
The Britain-based Syrian Observatory for Human Rights says that a full 2,287 of the more than 13,400 people killed since the uprising against Assad's regime began in March last year have died since the nominal start of the truce.
"We are all impatient and frustrated over the violence, over the killings. I am frustrated even more maybe than most of you," said Annan.
"I really want to see things move much faster than they have done," he told reporters in Beirut.
"Bold action has to be taken by President Assad in Syria to put real energy into the implementation of the six-point peace plan."
As the UN Human Rights Council held a special session to discuss last week's killings near Houla, reports emerged of the summary execution of 12 civilians at an army checkpoint in another central town on Thursday.
"The workers were on a bus when they were forced to stop at a checkpoint on the outskirts of Qusayr," said Salim Kabbani of the Local Coordination Committees, which organises protests on the ground.
"Regime forces tied their hands behind their backs and shot them."
Amateur video posted on YouTube by activists showed bodies lain out side by side, several with bullet wounds to the head.
Another video posted on Friday showed hundreds of people in Qusayr taking to the streets for a joint funeral for the slain workers.
A man bearing the Syrian independence flag led the cortege. Mourners chanted: "Oh God, we only have you to turn to," and: "We won't surrender, we won't surrender."
Green branches were laid on the white shrouds wrapped over the corpses as they were carried by pallbearers through the town.
The mass funeral came as protests were called across the country to protests against the Houla killings.
"These acts may amount to crimes against humanity and other international crimes," the UN rights chief told the Geneva meeting in a written statement.
She urged the international community to throw its weight behind Annan's peace mission.
"Otherwise, the situation in Syria might descend into a full-fledged conflict and the future of the country, as well as the region as a whole could be in grave danger," she said.
China's ambassador to the United Nations in Geneva Liu Zhenmin told the meeting that an immediate ceasefire was necessary, otherwise the situation could lead "perhaps even to civil war."
And after talks with UN chief Ban Ki-Moon in Istanbul, British Foreign Secretary William Hague voiced similar concerns.
"Both the secretary general and I -- and also the opposition in Syria -- think that Syria is on the edge of a catastrophic situation... on the edge of an all-out civil war and the collapse of Syria into sectarian strife," Hague told reporters.
He said that Britain was urging Russia to use its influence with the Assad government but added: "If it fails in the coming weeks, then we will need to return to the (UN) Security Council."
