President Donald Trump has said a deal to end fighting between the US and Iran is scheduled to be signed on Sunday, after Iran cast doubt on the timing.

In a post on social media, Trump said the Strait of Hormuz, a key shipping route, would be "open to all" once the deal is agreed.

Pakistan, a key mediator, also said the deal was expected to be finalised within 24 hours and they were "preparing for the electronic signing".

Before Trump's comments, Iranian foreign ministry spokesman Esmaeil Baghaei expressed caution over the timeline, saying: "We will have to wait and see about the exact date of the signing of the memorandum of understanding, although it will not be tomorrow."

In a post on Truth Social, Trump wrote: "The Deal is scheduled to get signed tomorrow, and immediately after it is signed, the Hormuz Strait is OPEN TO ALL."

In an apparent reference to Iran's enriched uranium stockpiles, Trump said that "at the appropriate time, when all is calm, we will go in and get the Nuclear Dust", adding it would later be destroyed.

For decades, Iran has been accused by Western countries of trying to build a nuclear weapon. It has denied the accusations saying its programme is for peaceful purposes - to generate electricity and for research purposes.

Trump also warned that if things would not "work out quickly, easily and smoothly", Washington had "the ultimate alternative, hopefully never to be used again!"

Earlier on Saturday, Pakistani Prime Minister Shehbaz Sharif said that "we are closer to a peace deal than ever before".

"With finalisation likely expected in the next 24 hours, Pakistan is preparing for the electronic signing of the peace deal immediately after, followed by technical level talks next week," Sharif wrote on X.

On Friday, Iran's Foreign Minister Seyed Abbas Araghchi said that a deal with the US was close.

The agreement envisaged an end to the conflict between Israel and Hezbollah in Lebanon, he said.

Araghchi told Iran's state TV that the deal included reopening the Strait of Hormuz and also the lifting of a US blockade of Iranian ports.

However, he said talks on Iran's nuclear programme would begin later.

US officials have confirmed some of the details of the agreement, saying economic benefits for Iran would depend on Tehran meeting its obligations.

Previous reports from the US had suggested Lebanon may not be part of this deal - with Iran reportedly insisting on it.

In recent months, variations of an agreement have been expected several times but have not been completed in the later stages.

The war began with US and Israeli strikes across Iran on 28 February, prompting Iran to attack Israel and US-allied states in the Gulf - as well as effectively closing the Strait of Hormuz, a key shipping route for the world's oil and liquefied natural gas.

Despite having agreed a ceasefire in April, the US and Iran have exchanged intermittent fire, including two rounds of tit-for-tat strikes this week.