Russia's Foreign Minister has said the situation in Syria is beginning to resemble civil war after defected soldiers attacked a key army base. Sergei Lavrov said the Arab League must call on all sides to end the violence. Last month Moscow vetoed a UN resolution condemning the violence and called for dialogue between the government and opposition groups. The Arab League has suspended Syria and given the government three days to end the "bloody repression". The League's 22 members said Syria must allow in a team of international monitors or face sanctions. The plan drawn up by the Arab League earlier this month calls on Syria to withdraw tanks from restive cities, cease its attacks on protesters and engage in dialogue with the opposition within two weeks. Mr Assad had agreed to the plan, but has failed to honour it and the violence has continued. More than 370 people have been killed since the announcement of the Arab League initiative on 2 November, say rights groups, in what appears to be the bloodiest month in the eight-month uprising. The UN says more than 3,500 people have died since protests started in March. Syrian authorities blame the violence on armed gangs and militants. On Wednesday, a group of defected soldiers known as the Free Syrian Army (FSA) were reported to have launched an attack on the notorious Air Force Intelligence building in the Damascus suburb of Harasta. The exact details of the attack were unclear, but unconfirmed reports said six government soldiers were killed. Mr Lavrov told Russian media: "We see television reports that say some new force, the so-called Free Syrian Army I believe, organised an attack on a government building." "This is already completely similar to real civil war," he said. "It is necessary to stop violence no matter where it comes from. It is an important thing because violence in Syria comes not only from government structures." Members of the Syrian National Council (SNC) opposition coalition who travelled to Moscow earlier this week failed to convince Russia to back calls for Mr Assad to stand down. The Kremlin instead urged the GNC to start a dialogue with Mr Assad's government, something SNC officials have said they will not do, blaming Mr Assad for the bloodshed. A number of countries have now withdrawn their ambassadors from Syria, and its diplomatic isolation is growing over its bloody eight-month crackdown on anti-government unrest.