US President Donald Trump said on Monday he had given orders to postpone ​any military strikes against Iranian power plants for five days, hours ahead of a deadline that threatened further escalation in the conflict now in its fourth week, reported Reuters.

Trump said in ‌a post on his Truth Social platform that the US and Iran had had "VERY GOOD AND PRODUCTIVE" conversations over the past two days about a "COMPLETE AND TOTAL RESOLUTION OF HOSTILITIES IN THE MIDDLE EAST".

In his message, written entirely in capital letters, he said he had instructed the defence department to postpone the strikes pending the outcome of the talks.

However, Iran's Fars news agency said after Trump's post that there was no direct communication with the US or through ​intermediaries.

Citing an unnamed source, Fars said Trump had retreated after hearing that Iran would respond by attacking all power plants in the region.

Iran’s foreign ministry denied that negotiations are underway with the US, reported The Associated Press, citing the Iranian state-owned newspaper IRAN.

"Remarks by the US president are part of efforts to reduce energy prices and buy time to implement his military plans," the newspaper said, according to the AP. "While there have been initiatives by regional countries to de-escalate tensions, Iran’s response has been clear: It did not start the war and all such requests should be directed to Washington," it stated.

Earlier in the day, CNBC news anchor Joe Kernen said Trump, in a phone call shortly after the post, had told him that “we are very intent on making a deal with Iran.”

However, Iranian state media, citing an unnamed “senior security official” in a post on Telegram countered Trump’s description of conversations, saying direct or indirect talks have not taken place between Washington and Tehran.

Iran showed no signs of backing down after President Donald Trump threatened to “obliterate” its power plants over the closure of the Strait of Hormuz, a critical trade route.

Tehran vowed to escalate strikes on US and Israeli infrastructure in the region, including energy and critical water desalination facilities, in response to any attack.

“There is been no negotiation and there is no negotiation, and with this kind of psychological warfare, neither the Strait of Hormuz will return to its pre-war conditions nor will there be peace in the energy markets,” state media reported the official as saying.

A source briefed on Israel's war plans said ​Washington had kept it informed of its talks with Tehran, and that Israel was likely to follow Washington in suspending any targeting of Iranian power ⁠plants and energy infrastructure.

The prime minister's office did not immediately respond to a request for comment on US talks with Iran or Washington's decision to hold off on striking some Iranian targets.

Oil drops, stocks surge on Trump statement

Trump's comments briefly sent the price of the Brent crude oil benchmark down around 13% to back below $100 a barrel. By 1155 GMT, however, it was back around $105.

Global markets also ​recovered sharply, with US stock futures reversing losses to gain more than 2%.

On Saturday, Trump had warned that Iranian power plants would be destroyed if Tehran failed to "fully open" the Strait of Hormuz to all shipping within 48 hours. Trump set a deadline of around 7:44 p.m. EDT (2344 GMT) on Monday.

Iran's Revolutionary Guards on Monday threatened retaliation, saying they would attack Israel's power plants and those supplying US bases across the Gulf region if Trump followed through ​with his threat.

More than 2,000 people have been killed in the war the U.S. and Israel launched on February 28, which has upended markets, driven up fuel costs, accelerated global inflation fears and ​convulsed the Western defence alliance.