His comments came following a U.S. decision to remove Ankara from the F-35 fighter jet programme after it began receiving delivery of the Russian S-400 missile defence system last week.

At 0454 GMT, the lira was at 5.6295 against the dollar, easing from a close of 5.6150 on Thursday.

The currency had firmed late on Thursday from levels around 5.7 earlier in the day after Trump said the United States is not currently looking at sanctioning Turkey over its purchase of the Russian defence system.

But Trump appeared to contradict that comment later, saying such a move on sanctions was in fact under consideration, sparking confusion at a tense time for relations between the two NATO allies.

"It's a very, very difficult situation for a lot of reasons," Trump said, when asked if he had ruled out sanctions on Ankara. "So we're looking at it. We'll see what we do."

The first parts of the S-400 air defence system were flown to the Murted military air base northwest of Ankara last Friday, sealing Turkey's deal with Russia.