President Donald Trump issued a fresh warning to Iran on Sunday, saying it had to move quickly towards a peace deal or "there won't be anything left of them."

Washington, locked in conflict with Tehran since US and Israeli forces launched major strikes on the Islamic republic beginning 28 February, has struggled to break an impasse and make any progress toward ending a war that has shaken the Middle East and sent energy prices climbing.

"For Iran, the Clock is Ticking, and they better get moving, FAST, or there won't be anything left of them," Trump wrote on his Truth Social platform. "TIME IS OF THE ESSENCE!"

The war has led to an effective blockade of the critical Strait of Hormuz, through which some 20 per cent of global oil exports pass in peacetime, and has drawn neighbors Israel and Lebanon into a deadly side conflict.