(Sharecast News) - Oil prices were sharply lower on Thursday as supply fears eased after US President Donald Trump toned down his aggressive language towards Iran's leaders over the killing of anti-regime protestors

Trump, who had threatened "very strong action" against the Islamic regime overnight claimed he had been told that killings in the crackdown on nationwide, protests were subsiding and he believed there was currently no plan for large-scale executions.

Brent crude gave up gains and plunged 3.3% lower to $64.27 a barrel while West Texas Intermediate tumbled by the same amount to $59.92 as supply fears eased.

Prices had risen on Wednesday on fears of Iranian supply disruptions due to a potential US attack on Iran and possible retaliation against US interests in the Gulf.

"We've been told that the killing in Iran is stopping - it's stopped - it's stopping. And there's no plan for executions, or an execution, or execution - so I've been told that on good authority," Trump told reporters, citing "very important sources on the other side", without offering further details and said the US had not yet verified the claims.

He had repeatedly threatened action against Tehran in recent days, saying the US was "locked and loaded" if Iran started to shoot at the protesters.

"There were supposed to be a lot of executions today," Trump said, adding that "the executions won't take place - and we're going to find out".

Trump was also under pressure from leaders in the Middle East worried about any retaliation from Iran against US bases in the region.

Earlier, the Iranian foreign minister, Abbas Araghchi, told Fox News "there is no plan" by Iran to execute people in retaliation for the anti-government protests. "Hanging is out of the question," he said.

Reporting by Frank Prenesti for Sharecast.com