MOSCOW (Reuters) - Russia’s defense ministry said on Tuesday its planes had carried out air strikes to support four rebel groups in Syria, saying it was working to try to unite the efforts of the Free Syrian Army and government troops against Islamic State.

The General Staff of the Russian army issued the statement as U.S. Secretary of State John Kerry held closed-door talks with Russian President Vladimir Putin and Russian Foreign Minister Sergei Lavrov in Moscow, with Syria topping the agenda.

It said over 5,000 Syrian opposition rebels were fighting against Islamic State in concert with the government forces of President Bashar al-Assad and that some rebels were supplying Russia’s air force with targets for air strikes.

It said it had conducted strikes in support of a group called “Ganim” which it said was part of the Free Syrian Army, as well as in support of a group called “Desert Lions”, another group called “Kalamun,” and another called “the Democratic Forces.”

“This work aimed at uniting the efforts of the government forces and other groups, which are interested in liberating Syria from international terrorists, will be continued,” the statement said.

The Kremlin has sent mixed signals on the Free Syrian Army with some government officials saying Russia is arming them and others denying that. The FSA itself has denied receiving any Russian help, complaining that Russia is continuing to bomb it instead.

The Russian defense ministry said more than 150 Syrian opposition groups were helping support the land operation conducted by the Syrian government army.

“Actions by the so-called ‘moderate opposition’ against Islamic State have assisted the success of the land operation conducted by Syria’s armed forces,” it said.

A senior Western diplomat who declined to be named was skeptical of Russia’s assertions about its collaboration with the FSA.

“That’s not reality on the ground,” the diplomat said. “The FSA categorically denies it and it’s pure propaganda to try and divide the opposition.”