Moscow, one of Assad’s main remaining allies more than a year into an uprising against his rule, has repeatedly accused the Syrian opposition of blocking efforts to resolve the conflict.

Russia’s foreign ministry said it was pleased to learn that Assad had accepted the peace plan, which calls for a cease-fire and withdrawal of government forces from cities and towns ahead of political dialogue.

“It is extremely important in this context for Syrian opposition groups to follow the example of Damascus and clearly declare their agreement with ... the peaceful resolution proposals of the UN-Arab League special envoy,” it said in a statement.

“Obviously, much also depends now on external players, particularly those that are capable of influencing the opposition in a positive way,” the ministry added.

Russia and China have shielded Assad from UN Security Council condemnation by vetoing two Western-backed resolutions condemning his government for the bloodshed.

Annan’s six-point plan does not specify that Assad must step aside as a condition for a political dialogue in Syria.

That pleases Russia, which accuses the United States and its allies of using humanitarian concerns to push out governments they do not like. Moscow has said such a condition would amount to unjustified foreign interference in a sovereign state.

Syria is Moscow’s firmest foothold in the Middle East. Damascus buys billions of dollars worth of weapons and hosts a Mediterranean supply and maintenance facility that is Russia’s only naval base outside the former Soviet Union.

Syria’s splintered opposition leaders reunited under the Syrian National Council (SNC) umbrella group on Tuesday during a meeting in Istanbul.

But they remained skeptical about Annan’s plan and said they did not believe Assad was interested in negotiating an end to the conflict.