Russian President Vladimir Putin said Russia had no plans "right now" to put combat troops on the ground in Syria, but will continue backing the Syrian government.

The Russian leader, speaking in an interview broadcast on Sunday on the eve of his meeting with US President Barack Obama, also sharply criticized US military support for Syrian rebels, describing it as not only illegal but counterproductive.

His statements show how far apart Russia and the US remained on Syria going into Monday's meeting between the two presidents. Putin and Obama were set to meet on the sidelines of the UN General Assembly, after both address the annual gathering of world leaders.