"The government will evaluate the plans and decide whether such a move is necessary," Turkish television stations quoted Erdoğan as telling reporters on his plane as he returned from an official visit to Qatar.

A presidency official confirmed that Erdoğan had made such remarks but did not specify where along the border the zone might be established and gave no further details.

Turkey, a member of the NATO military alliance, has made clear it does not want a frontline role in a military coalition which the United States is trying to assemble to fight ISIS militants in both Iraq and Syria.

Government officials have said Turkey is hamstrung by 46 hostages, including diplomats, soldiers and children, being held by ISIS after they were seized from the Turkish consulate in the northern Iraqi city of Mosul in June.

U.S. officials have said several Arab countries have offered to join air strikes against ISIS but declined to name them. Ten Arab states committed in Jeddah last week to the military coalition without specifying what action they would take.