The Russian Foreign Ministry said on Sunday that Syrian President Bashar al-Assad had left office and departed the country after giving orders there be a peaceful handover of power.

In a statement, the ministry did not say where Assad was now and said Russia has not taken part in the talks around his departure.

"As a result of negotiations between Bachar Assad and a number of participants in the armed conflict on the territory of the Syrian Arab Republic, he decided to resign from the presidency and left the country, giving instructions for a peaceful transfer of power.

"Russia did not participate in these negotiations," the ministry said.

Moscow was extremely worried by events in Syria and urged all sides to refrain from violence, it said.

"We urge all parties involved to refrain from the use of violence and to resolve all issues of governance through political means," the statement said.

"In that regard, the Russian Federation is in contact with all groups of the Syrian opposition."

It said Russia's military bases in Syria had been put on a state of high alert, but that there was no serious threat to them at the current time.