Syrian, Iranian and Russian defence ministers meet in Tehran

Syrian regime defence officials will hold talks in Tehran with their Iranian and Russian allies to discuss Damascus' ongoing offensive against the Islamic State group, state media has said.

Syrian regime, Iranian and Russian defence ministers met in Tehran to discuss further military offensives in Syria.

Moscow has sent war planes and special forces to help prop up President Bashar al-Assad's regime, while Tehran's forces have played a crucial role in supporting Damascus, sending thousands of fighters and advisers to the frontlines.

Syria's General Fahd Jassem al-Freij visit to Tehran comes as the Damascus regime steps up its campaign against both IS and rebel fighters in second city Aleppo.

Russian Defence Minister Sergei Shoigu travels to Tehran after Moscow pledged to step up its air raids on rebel areas in and around Aleppo, accusing non-jihadi rebels of failing to deliver on a February ceasefire pledge to break ranks with al-Qaeda's Syria affiliate al-Nusra Front, which is not party to a ceasefire agreed in March.

The talks are being held at the invitation of Iran's General Hossein Dehghan, the state IRNA news agency said.

Tehran has provided Damascus with military and financial support ever since the uprising against Assad's regime erupted more than five years ago.

Moscow's military intervention began last September and hundreds of air raids have significantly improved the regime's position.

Russian forces helped regime troops to recapture the famed ancient city of Palmyra in March and are now backing a push towards Syria's largest dam at Tabqa in the Euphrates Valley.

Joint support

The visit comes as AFP reported that Russia, Iraq and the Syrian regime are cooperating with the US over military operations against IS.

The US is supporting a Kurdish-led offensive in northern Raqqa against the Islamic State group, and also towards the Tabqa Dam.

This has led to the creation of a joint operations room in Baghdad.

"There is a joint operations room in Baghdad where the Iraqis and the Syrians are coordinating with the support of the Americans and the Russians," a Syrian regime source told AFP.

He said it would be "impossible" for the US and Russia to back their respective ground allies if they did not coordinate.

On Monday, Russia's Foreign Minister Sergei Lavrov vowed air support around Aleppo for regime troops.

"(The Americans) know that we will be actively supporting the Syrian army from the air to prevent terrorists from seizing territory," said Lavrov.

Washington "is asking us and Syrian leadership to delay air strikes" until opposition forces are separated from jihadists of IS and Nusra, he said.

"We believe there has been more than enough time (for that)," Lavrov said, while adding "there won't be any surprises for the Americans".

In Washington, a State Department spokeswoman insisted US officials are in talks with groups on the ground to encourage moderate elements to separate themselves from Nusra.

"We would reiterate that Russia and the Assad regime need to distinguish between the terrorists and parties to the cessation of hostilities," said Elizabeth Trudeau.