Western powers maintained that diplomatic solutions like the Annan plan were preferable to military intervention in Syria, even as UN Secretary-General Ban Ki-moon warned that massacres of civilians, such as the one perpetrated in Houla last weekend, could plunge Syria into a devastating civil war.

The US, UK, France and China on Thursday each urged the world to give UN-Arab League envoy Kofi Annan's peace plan for Syria more time to work, though appetite for a possible military intervention should the plan fail varied substantially between them.

Speaking to students in Denmark, US Secretary of State Hillary Clinton laid out arguments against armed intervention in Syria.

"We are trying to keep pushing all the pieces to support Kofi Annan as an independent voice because the Syrians are not going to listen to us," she said. Above all, she stressed there was no international support because of Russian and Chinese opposition at the UN Security Council, where they have twice vetoed resolutions on Syria.

Syria, she said, "may listen, maybe, to the Russians, so we have been pushing them."

Chinese Foreign Ministry spokesman Liu Weimin told a daily news briefing that, "China believes that the situation in Syria currently is certainly very complex and serious."

"But at the same time, we believe that Annan's mediation efforts have been effective and we ought to have even more faith in him and give him more support," he added.

France said it is willing to consider all options for resolving the crisis in Syria but only within the framework of the United Nations Security Council, the foreign ministry said on Thursday.

Click for full JPost coverage

Asked about comments by the US Ambassador to the United Nations, Susan Rice, who on Wednesday suggested that member states may end up having to act independently if the Council does not swift action to end the crisis, the ministry said: "France supports the UN special envoy and Arab League's plan, without ruling out any option for ending the crisis, within the framework of the Security Council."

Britain was in agreement. "Nobody is enthusiastic about the military option," UK Ambassador to Israel Matthew Gould said in a Thursday interview with Israel Radio, specifying that pushing for Syrian cooperation with the Annan plan was preferable. "There's no rush to military action."

While saying that Britain is "disgusted" with Syria's violence, particularly the slaughter of 108 people in Houla last Friday, he added that "it won't be helpful to start speculating" on military options.

"The problem is we do have to work through the UN security council," Gould said, but added that the unsavory images coming out of Syria and increasing support from the Arab League would make it more difficult for countries to block steps at the Council.

Fears of a civil war

UN Secretary Ban cited fears raised on Tuesday by Kofi Annan, the joint special envoy for the Arab League and United Nations, that Syria may have already reached a "tipping point" following the Houla massacre.

"The massacre of civilians of the sort seen last weekend could plunge Syria into catastrophic civil war - a civil war from which the country would never recover," the UN secretary-general told a conference in Istanbul.

Syria's state media said it released 500 prisoners who were arrested on suspicion of involvement in the 14-month-old revolt, on Thursday, two days after peace envoy Kofi Annan urged President Bashar Assad to free detainees.

"500 people involved in the events taking place in Syria, without blood on their hands, have been released," a newsflash on state TV read.

Assad rejects ultimatum

The commander of Syria's main armed rebel group urged Annan to formally announce that his seven-week-old ceasefire plan had failed, allowing rebels to resume attacks on President Bashar Assad's forces, Al Jazeera television reported.

Asaad also dismissed a 48-hour deadline declared on Wednesday by senior Free Syrian Army officer for Assad to comply with the plan.

"There is no deadline, but we want Kofi Annan to issue a declaration announcing the failure of this plan so that we would be free to carry out any military operation against the regime," Asaad told Al Jazeera, adding that the rebel forces had so far honored their commitments to the plan.

Please LIKE our Facebook page - it makes us stronger