Islamic State leader Abu Bakr al-Baghdadi arrived at the location in Syria where he was reportedly killed early on Sunday in a U.S. raid some 48 hours before the operation, a senior Turkish official said.

The Turkish army had advance knowledge of the U.S. operation in Syria's Idlib, the official said, adding that Turkey would continue to coordinate its actions on the ground with the "relevant parties".

A U.S. official, speaking on condition of anonymity, earlier told Reuters that Baghdadi had been targeted in the overnight raid but was unable to say whether the operation was successful.

U.S. President Donald Trump is expected to make a "major statement" later on Sunday.