Senior Russian official confirms Assad in Russia: NBC

Assad was transported to Russia "in the most secure way possible" amid the sudden collapse of his regime, Deputy Foreign Minister Sergei Ryabkov said.

A senior Russian official told US broadcaster NBC on Tuesday that deposed Syrian leader Bashar al-Assad is being hosted in Russia, giving Moscow's first public confirmation of his whereabouts.

Moscow had long backed ousted President Bashar Assad's government in Syria's civil war. (AP)

Assad was transported to Russia "in the most secure way possible" amid the sudden collapse of his regime as rebels raced toward Damascus, Deputy Foreign Minister Sergei Ryabkov said.

The Kremlin had initially refused to comment on reports in Russian state media that Assad had been granted asylum in the country.

Moscow had long backed his government in Syria's civil war.

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Ryabkov did not detail where exactly Assad was in Russia, saying "I have no idea what is going on with him right now."

It "would be very wrong for me to elaborate on what happened and how it was resolved," he said.

Assad fled Syria as the Islamist-led opposition alliance swept into the capital Damascus over the weekend, bringing a spectacular end on Sunday to five decades of brutal rule by his clan.

The renewed rebel offensive, launched late last month, broke through the long-frozen frontlines of the conflict, with the rebels taking the capital Sunday.

Asked if Assad would be handed over to stand trial for the litany of crimes he and his government are accused of -- including disappearing critics and using chemical weapons -- Ryabkov responded that "Russia is not a party to the convention that established the International Criminal Court."

Russia maintains a naval and air base in Syria, though their futures are now uncertain after Assad's fall.