Syria's main opposition group said on Saturday that it was pulling out of international talks and demanded world action to stop the slaughter of Syrians, after missiles slammed into the cityof Aleppo killing dozens.

The Syrian National Coalition's decided to boycott talks with world power after announcing plans to form a government to run "liberated areas" of Syria, in what analysts said was a bid to boost its credibility and win more support from the international community.Coalition chief Ahmed Moaz al-Khatib said the group's withdrawal frommeetings abroad was "a message of protest to all governments of the world, Arab and non-Arab, that can see how the Syrian people are being killed, while they merely look on."

He was speaking as the conflict, which has cost the lives of more than70,000 people according to the UN, is set to enter its third year, with no end in sight.Condemning the "international silence" on the bloodshed in Syria, which it charged "amounts to participating in two years of killings," the opposition said Friday that it would not attend meetings in Italy, Russia and the United States.It singled out Damascus ally Russia for blame, saying its leaders were"ethically and politically responsible because they continue to support the (Syrian) regime with weapons."

The group had been due to attend a Friends of Syria meeting in Rome on Thursday, while Khatib had also been invited to Moscow, and to the United States."We cannot visit any country until there is a clear decision on thissavage, aggressive regime," Khatib said of the government of Syrian President Bashar al-Assad.Britain urged the opposition to reconsider its decision to pull out of theRome, Washington and Moscow meetings, insisting "now is not the time to give up" on talks.

A Foreign Office spokeswoman said London was "preparing a further offer of support" for the National Coalition at the meeting in Rome.But opposition spokesman Walid al-Bunni insisted that statements should be "accompanied by action" and said the world had a duty to protect Syrians from the regime of the "butcher" Assad."If you are our real friends, help us to stop the massacres that are being committed against our own people," Bunni said, challenging the United States to honour what he said were promises of support for democracy in Syria.

The opposition has repeatedly asked the international community to arm the rebels but Bunni fell short of repeating the demand, which Western powers have balked at, fearing the growing influence of radical Islamists.