Iran says it is negotiating with Oman to reach “an understanding” over a temporary route through the Strait of Hormuz to allow commercial shipping to resume.

The statement came after US President Donald Trump said new talks on ending the war in Iran would begin on Monday – and that he had called off “massive” strikes on the country for this purpose.

Trump did not specify who would take part in the talks. Iran, however, said it was not negotiating with the US – and had no plans to do so.

Tehran’s denial appears to have enraged the US president, who later wrote on his Truth Social media platform that Iran’s leadership was “unbelievably duplicitous”.

“They ask for a meeting, some would say ‘beg,’ talks begin, with more scheduled in the immediate future, and they say, openly and proudly, that they’re not having any discussions, that nothing is being talked about, and they’re only dealing with ‘Oman.’,” Trump wrote.

At the weekend, Trump had said the “perimeters” of a deal had been agreed – and would include reopening Hormuz, the vital waterway whose closure by Iran has sent oil prices soaring.

Tehran has repeatedly closed off the strait since the US and Israel started attacks on the country in February.

But Trump insisted on Monday that the strait was controlled by the US and no ships would be allowed to reach Iran “unless a Deal, or Total Surrender, is accomplished”.

Speaking on board Air Force One on Sunday, he said Iran “knew the extent” of the planned US strikes “because they saw it forming”, adding: “We’re talking to them in the form of a negotiation. It begins tomorrow afternoon.”

Trump declined to outline a deadline for a deal to be struck with Tehran, adding: “We’ll just see how it is. We’re ready to go anytime we want… I’m not looking to kill people.”

Trump added that Saudi Arabia’s Crown Prince Mohammed Bin Salman – as well as US partners such as the United Arab Emirates and Qatar – had urged him against conducting strikes over the weekend.

“We were all set to go,” Trump said. “The reason they asked is [that] they think there’s a deal,” he said. “There’s a deal on Hormuz, and there will be a deal on the nuclear.”

Global oil prices fell on Monday morning in Asia trading after Trump’s announcement. Brent Crude oil was down by 4.5% at $83.98 (£62.26), while US-traded oil was 4.6% lower at $80.74 (£59.85).

Energy prices have fluctuated since the conflict started on 28 February as traders reacted to disruptions to shipping through the Strait of Hormuz.

Around 20% of the world’s crude oil and liquefied natural gas (LNG) usually flows through the strait.

Vessel-tracking data from trade intelligence company Kpler suggests commercial shipping through the strait has slowed.

According to the data, 51 vessel crossings occurred through the strait between 30 July and 2 August. This is a drop of around 28% compared to the previous 4 days, in which 71 crossings were recorded through the strait.

Talks to end the conflict – mostly facilitated by mediators – collapsed last month, ending a ceasefire agreed in April.

Trump has repeatedly vowed that a negotiated end to the war is near, only for tit-for-tat strikes to resume.