Moscow takes Iran's, Syrian regime side of conflict and warns that ISIS 'could go very, very far' if not stopped.

Russia on Tuesday urged a US-led coalition fighting against the Islamic State group to coordinate their air raids with the Syrian government, warning that jihadists could go "very far" if not stopped.

"It is absolutely clear to me it was a mistake -- still is -- not to coordinate the air strikes with the activities of the Syrian army. That's what we believe must be done," Russian Foreign Minister Sergei Lavrov told Bloomberg Television in an interview.

"And that is what unfortunately our American colleagues cannot accept for ideological considerations."

Lavrov spoke as the Western coalition gathered for Paris crunch talks involving Iraq to discuss the advance of ISIS jihadists who have declared an Islamic caliphate in large parts of Syria and Iraq they now control.

Moscow's top diplomat whose country is among the main backers of the Syrian President Bashar al-Assad, warned that the ISIS terrorists could go "very far, very far" if not stopped.

"They already make a lot of progress in Iraq, in Syria. They just took the Idlib province," he said, noting that the terrorists were expanding into Libya.

"And even in northern Afghanistan which is very close to Cental Asia which is next door to Russia."

Asked if ISIS could take over all of Syria, Lavrov declined to answer directly, adding however he was not optimistic about the future of the region if things remain as they are.

"If people continue to acquiesce with what is going on, and continue to acquiesce with those who categorically refuse to start the political process until Bashar Assad disappears then I am not very optimistic for the future of this region," he said.

"Because these people put the fate of one person whom they hate on top of the fight against terrorism," Lavrov said.

"We have been through this repeatedly. Saddam Hussein was the one person after whom the United States went and they ruined the country."

"Gaddafi is the same," he said, referring to Libya's fallen dictator.

Asked if Russia would support ground troops in the Middle East, Lavrov declined a direct response.

"Do you believe that the American troops are the only troops who can do the trick? They've been to Afghanistan, they've been to Iraq and look where Afghanistan and Iraq are now."

AFP contributed to this report.