Syria said on Monday, Aug 25, it would cooperate in any international effort to fight Islamic State militants, after Washington signaled it was considering extending the battle against the group into Syrian territory, Reuters reported.

Russia, the most prominent foreign backer of Syrian President Bashar al-Assad, also urged Western and Arab nations to overcome their distaste of the government in Damascus and engage with it to fight the hardline insurgents.

Syrian Foreign Minister Walid al-Moualem held open the possibility of working with a range of countries, including the United States, Britain and Saudi Arabia, all of which supported the uprising against Assad.

Moualem presented his country as a vital partner in a war against Islamic State, which has seized areas of Syria and Iraq and declared a "caliphate" in the territories it controls.

"Syria, geographically and operationally, is the center of the international coalition to fight Islamic State," Moualem said in a televised news conference. "States must come to it if they are serious in combating terrorism," he added.

Asked about the prospect of U.S. air raids against Islamic State inside Syria, Moualem said any strikes would have to be coordinated with Damascus. "Anything outside this is considered aggression," he told reporters.

Asked if Syria was ready to work with the United States and Britain in fighting the group, he said: "They are welcome."

He also called for intelligence sharing with neighboring states and suggested cooperation would be possible with Saudi Arabia, another major backer of the anti-Assad uprising that has shown increasing alarm about Islamic State.

Islamic State, an offshoot of al Qaeda which draws some of its strength from foreign fighters, has emerged as the strongest group in the insurgency. Its thousands of fighters control roughly a third of Syria, with territory in the north and east.