President Vladimir Putin on Thursday declared his country's Syria mission a resounding success, but stressed Russia would continue to support the Syrian government and could build up its military presence in the region again within hours if necessary.

Speaking in the Kremlin at a medal ceremony for military personnel who served in Syria, Putin sought to dampen any talk of a rift with Damascus, saying Moscow's partial withdrawal from Syria had been agreed with President Bashar al-Assad.

Although he stressed his preference for a negotiated diplomatic solution to the conflict, he made clear Russia could easily scale up its forces again.

"If necessary, literally within a few hours, Russia can build up its contingent in the region to a size proportionate to the situation developing there and use the entire arsenal of capabilities at our disposal," said Putin.

The Russian leader on Monday ordered the bulk of the Russian military contingent in Syria to be pulled out after five months of air strikes, saying the Kremlin had achieved most of its objectives.

Russia would finish withdrawing most of its Syria aviation strike force "any day now" and no later than by the end of this week, Viktor Bondarev, the head of the Russian air force, told the Komsomolskaya Pravda newspaper in an interview published on Thursday.