MOSCOW: Russian President Vladimir Putin received his Syrian counterpart Bashar al-Assad on Monday for the first time since 2018 and criticised foreign forces that are in Syria without permission or a U.N. mandate - a rebuke of the United States and Turkey.

Putin is Assad's most powerful ally in the decade-long Syrian conflict; his deployment of Russia's air force in 2015 helped to turn the tide in Assad's favour, allowing him recover most of the territory lost to insurgents.

However, Turkish forces are now present in much of the north and northwest, helping to shore up the last major bastion of anti-Assad rebels, and U.S. forces are supporting Kurdish-led militias who control parts of the east and northeast.

Assad, who has also been assisted by Iran during the conflict, has made few trips abroad since the war began in 2011.

Putin told him the main problem in Syria was the presence of foreign forces without permission or a U.N. mandate, "which clearly runs counter to international law", the Kremlin said on Tuesday.

This "undermines your ability to use your best efforts to consolidate the country and promote recovery at a pace that would have been possible if the legitimate government controlled the entire country". The Syrian state views the U.S. and Turkish forces as occupiers, while Russian forces and Iranian-backed militias are there at the government's invitation.