The Russian jets bombed 24 marks, including command posts, ammunition stores and anti-aircraft artillery in Syria on Tuesday, with assistance from forces who are not allied with the regime.

"The coordinates of all of these targets were given to us by opposition representatives," senior military official Andrei Kartapolov said.

Moscow also announced it had set up "working coordination groups" with moderate factions, aimed to boost the fight against the "Islamic State." However, the officials did not provide identities of individuals or factions involved.

"Such close cooperation will allow us to unite the efforts of the government troops with other patriotic forces in Syria that used to be in the opposition and act as a united front against the common enemy - international terrorism," the defense ministry said in a statement.

The Russian Foreign Ministry confirmed the contacts with the opposition, saying they were "useful" for both "fighting terrorism and promoting the political process."

Moscow is the strongest military ally of Syrian President Bashar al-Assad's regime, and has been conducting an aerial campaign against the "Islamic State" since late September. Russian jets have hit 2,084 targets in 1,631 sorties since the airstrikes started, according to the Kremlin.

The US and its allies accuse Moscow of also targeting the moderate opposition in an effort to boost Assad's forces.

Sky safety test

The fate of the Syrian president has been a major stumbling block the road towards diplomatic solution in the civil war. While Russia and Iran support Assad, the US and other Western powers have been calling for his immediate resignation.

However, both blocs have shown signs of flexibility during recent weeks.

On Tuesday, Moscow said it was not a matter of principle to keep Assad in power.

On the same day, Russian and American jets conducted tests in skies over Syria, aimed to avoid midair collisions. The pilots also exchanged information on flight plans in both English and Russian.

dj/jr (AFP, Interfax, Reuters)