Moscow says Russia's air force in Syria is ready to provide cover for the Free Syrian Army, the Western-backed opposition group battling President Bashar al-Assad, in its fight against the Islamic State (IS) extremist group.
"We are ready to also support patriotic opposition, including the so-called Free Syrian Army, from the air," Russian Foreign Minister Sergei Lavrov said in an interview aired on October 24.
Russian air strikes in Syria began on September 30.
In the interview with the Rossiya 1 television channel, Lavrov also said parliamentary and presidential elections must be part of any political settlement of the Syrian crisis.
On October 22, Russian President Vladimir Putin said Assad had told him he was ready to talk to armed opposition groups if they are committed to dialogue and to combating the IS group.
Putin made the remarks two days after Assad made a surprise visit to Moscow.
Some Western governments, led by the United States, have criticized Russian air strikes in Syria, saying they have mainly targeted opponents of Assad and, as a result, have strengthened the hand of IS militants.
Lavrov said Russia expected the West to help Moscow identify areas controlled by the moderate opposition.
"The Americans' refusal to coordinate their antiterrorist campaign with us is a major mistake," Lavrov said.
He said Russia is "ready for this coordination to be as deep as possible."
Meanwhile on the ground, Syrian government forces clashed with IS militants on October 24 in a bid to retake a key supply line to the country's second city, Aleppo, a monitoring group said.
The Syrian Observatory for Human Rights reported heavy casualties on both sides.
Backed by Russian air strikes, the army has recaptured territory south of Aleppo in recent days and is seeking to break an IS siege of the Kweyris airbase to its east.
Government forces have also been on the attack in the central provinces of Hama and Homs.