(Adds quotes, details)
By Mariam Karouny and Sylvia Westall
BEIRUT, Aug 25 (Reuters) - Syria said on Monday it would cooperate in any international efforts to fight Islamic State militants in the country, after Washington signalled it was considering extending the battle against the group into Syrian territory.
Foreign Minister Walid al-Moualem, whose government has been shunned by the West, presented his country as a vital partner in the war against Islamic State that has seized wide areas of Syria and Iraq.
"Syria, geographically and operationally, is the centre 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 strikes against Islamic State inside Syria, Moualem said his government was ready to cooperate with any country fighting militants. But any air raids mounted without Damascus's approval would be viewed as hostile acts. "Anything outside this (cooperation) is considered aggression," he said.
The White House signalled on Friday it was considering taking the fight against Islamic State into Syria after days of air strikes against the group in Iraq and the beheading of an American journalist.
But Washington has also supported a more than three-year-old insurgency against Assad and there has been no sign of any shift in U.S. policy towards the Syrian leader.
"He's part of the problem," Ben Rhodes, President Barack Obama's deputy national security adviser, said in a broadcast interview last week. Last year Washington came close to bombing Syria after accusing Assad's forces of using chemical weapons.
Islamic State, an offshoot of al Qaeda, has emerged as the strongest group in the insurgency against Assad. It controls roughly a third of northern and eastern Syria and has since grabbed territory in neighbouring Iraq, declaring a cross-border "caliphate". (Reporting by Mariam Karouny; Editing by Andrew Heavens)