Syria's opposition National Coalition said it was pulling out of several international meetings to protest at the "international silence" despite the slaughter of civilians in the conflict. The announcement came after the coalition had said it would form a government to run "liberated areas" of Syria, and as international condemnation mounted against Thursday's devastating attacks in Damascus that left around 100 people dead. In further violence Friday, monitors said more than 12 people had been killed when buildings collapsed after a missile strike on the city of Aleppo. The National Coalition said it was pulling out of meetings in Italy, Russia and the United States, to protest against the "shameful" lack of international condemnation of "crimes committed against the Syrian people". The group had been due to attend a Friends of Syria meeting in Rome next Thursday where US Secretary of State John Kerry is also expected. National Coalition chief Ahmed Moaz al-Khatib had also been invited to Moscow. "The international silence on the crimes committed every day against our people amounts to participating in two years of killings," said the statement. "We hold the Russian leaders in particular ethically and politically responsible because they continue to support the (Damascus) regime with weapons," the National Coalition added. Already Friday, coalition spokesman Walid al-Bunni had announced plans for a government for "liberated areas" following a meeting in Cairo. They would decide on its composition and choose its leader at a meeting on March 2, he added. Coalition members said the meeting would be held in Istanbul, while Bunni said it was hoped the government would be based in rebel-held territory inside northern Syria. The opposition umbrella group had been discussing a proposal by chairman Ahmed Moaz al-Khatib to hold direct talks with President Bashar al-Assad's regime. The group has refused to meet Assad himself, or the security or military command. Khatib himself has made it clear the offer was only to those without "blood on their hands". The Arab League and the United States, vocal critics of the Assad regime, have welcomed the initiative, as have Iran and Russia, both close to the Damascus regime.