International envoy Kofi Annan said on Friday he was 'frustrated and impatient' a week after a massacre in Syria of 108 people shocked the world, but Russia said his peace plan was still the best hope for Syria.

Speaking after separate talks with German Chancellor Angela Merkel and French President Francois Hollande, President Vladimir Putin urged countries to continue to back Annan's peace initiative as the best way to avoid full civil war.

'Annan is a very experienced and respectable person and we must do everything for his mission to succeed. I think it is counterproductive to announce his mission as a failure in advance,' Putin told a news conference in Paris.

'Sanctions don't always work. The main thing we need to do is to prevent the situation from developing under the worst scenario and not let a civil war take place.'

Damascus says it wants Annan's plan to succeed so the crisis can be resolved through political talks.

But Syrian rebels, who agreed to Annan's April 12 truce plan, have urged him to declare the plan dead, freeing them from a commitment that both sides have repeatedly violated.

The plan calls for the government to pull heavy weapons back from towns and cities, after which both sides are to end violence and begin a dialogue, but it has stalled at the first hurdle.

Although refusing to declare the ceasefire a failure, Annan welcomed any further steps from the UN Security Council.

'If there are other options on the table, I will say 'bravo' and support them,' Annan told reporters after talks in Beirut with Lebanese Prime Minister Najib Mikati.

Hollande said Syrian President Bashar al-Assad's government had disqualified itself from ruling Syria.

'No solution to this crisis is possible without the departure of Bashar al-Assad,' he said, standing next to Putin. 'I believe that more sanctions are an essential part of a political solution.'

Outrage at last Friday's mass killings in Houla, documented by UN observers, prompted a host of Western countries to expel Syria's senior diplomats, and to press Russia and China to drop their vetoes and allow tougher UN Security Council action.

China and Russia back Annan's plan, the only broadly accepted initiative to halt the bloodletting in Syria, and reject any intervention, UN-backed sanctions, or proposal .

The 193-nation UN General Assembly is planning to meet next week to discuss the crisis in Syria and the massacre in Houla. Ban, Annan and UN human rights chief Navi Pillay are likely to address the assembly on Thursday.

Annan will also speak to the 15-nation UN Security Council that day about the lack of progress implementing his peace plan.

Arab League Secretary-General Nabil Elaraby urged the Council to 'move quickly to end all acts of violence taking place in Syria, and to take the necessary measures to protect Syrian civilians', according to a letter leaked to media.

That proposal is similar to language the Council used last year to authorize military intervention in Libya, which Russia did not veto but has criticized ever since. Russia has vowed to prevent Syria from becoming another Libya, where it says Nato airstrikes directly supported rebels and led to 'regime change'.

Russia, China and Cuba all voted against a resolution passed by the 47-member Human Rights Council in Geneva on Friday condemning Syria for the massacre in the Houla region and calling for a U.N. investigation to gather evidence for possible criminal prosecution.

Russia's Foreign Ministry backed the Syrian government's assertion that the massacre was the work of anti-government forces intent on undermining peace efforts. But in Paris, Putin took a different line.

He appeared to accept that Syrian government forces had at least played a part in killing civilians, but said the rebels were guilty of similar acts.

'How many peaceful civilians were killed by the opposite side? Did you count? The count goes into the hundreds there too. Our goal is make peace between the sides of the conflict.'

'We are not for Assad, not for his opposition,' he said. 'We want to reach a situation where violence ends and a large-scale civil war is averted.'

US Secretary of State Hillary Clinton will meet Russian Foreign Minister Sergei Lavrov this weekend, Donahoe said.

Clinton said Washington was ready to cooperate with Moscow if it was ready to work on a political transition in Syria.

Putin denied that Russia, which supplies Syria with weapons, was providing the government with the means to crush rebels, brushing off Clinton's comment that its latest shipment to Syria was 'reprehensible'.

The Syrian Observatory for Human Rights, a British-based monitoring group, meanwhile said at least 20 people had been killed in clashes in Syria on Friday. It said hundreds of thousands of civilians had attended opposition protests around the country.

A day before, a dozen workers were killed near the western town of al-Qusair when gunmen loyal to Assad ordered them off a bus and shot them, activists said. Syrian media blamed 'terrorists'.

Video released by activists showed the corpses of 12 men, two of them with the tops of their heads shot away, laid out on the ground near the town of al-Qusair, which like Houla is about 20 km from the city of Homs, a hotbed of opposition to Assad.

Hamza Al-Buweida, a local opposition activist, said a survivor had told him the dead men had been returning from work at a fertilizer company in al-Buweida al-Sharqiya.

'They stopped, as usual, at a Syrian army checkpoint. But about 300 meters after the checkpoint a yellow car with four armed shabbiha (pro-Assad militia) stopped their car,' he told Reuters over Skype.

'They took money off the men and then killed them one by one with gunshots to the head. More than 300 bullets were found in the bodies.'

It was impossible to verify Buweida's account. Syria has restricted journalists' access since the start of the uprising against Assad 15 months ago.

Activists say 50 to 100 people have died each day this week, including civilians, soldiers and anti-Assad rebels.

UN High Commissioner for Human Rights Navi Pillay said those who carried out the slaughter in Houla could be prosecuted for crimes against humanity.-Reuters