Russian warships have joined in strikes in Syria with a volley of cruise missile attacks, as Russian President Vladimir Putin pledged his air force would back a ground offensive by government forces.
Ships from the Caspian Sea fleet launched 26 cruise missile strikes against 11 targets on Wednesday, Moscow said.
The Russian president also stressed the need for cooperation with a US-led coalition fighting Islamic State jihadists, saying that without cooperation from the US, Turkey and Saudi Arabia the intervention was unlikely to work.
Russian efforts "will be synchronised with the actions of the Syrian army on the ground and the actions of our air force will effectively support the offensive operation of the Syrian army," Putin said at a meeting with Defence Minister Sergei Shoigu.
Russian forces have struck 112 targets in war-torn Syria since last week launching a bombing campaign that Moscow says is targeting the IS group, Shoigu told Putin in the televised briefing.
"Strikes have hit 112 targets from September 30 until today," Shoigu said.
"The intensity of the strikes is increasing."
In a sign that Russia was ramping up its involvement, Shoigu said that four Russian warships had hit sites in Syria on Wednesday with cruise missiles.
"In addition to the air force, four warships of the Caspian flotilla have been involved," Shoigu said, adding that the warships had carried out 26 cruise missile strikes against 11 targets.
Russia began air strikes in Syria a week ago following a request by long-standing ally President Bashar al-Assad.
Moscow insists it is hitting IS targets but the US and its allies fear that Moscow is aiming to bolster Assad's regime.
Putin also said that French leader Francois Hollande had suggested a possible plan to get government forces to combine efforts with the Western-backed Free Syrian Army, the main moderate opposition group fighting the Damascus regime.
A Hollande aide later denied he had said any such thing.
"The president spoke of the necessary presence of the Syrian opposition around a future negotiating table. The rest is not a French idea," he told reporters in Strasbourg.
Meanwhile, the US on Wednesday insisted it was not cooperating with Russia's air strikes in Syria with Defence Secretary Ashton Carter describing them as "a fundamental mistake".
"I have said before that we believed that Russia has the wrong strategy - they continue to hit targets that are not ISIL. We believe this is a fundamental mistake," Carter told a press conference in Rome.