President Donald Trump has threatened to bomb Oman - a US ally - if it "gets in the way" of his administration's own talks with Iran, Fox News reports.

The US and Oman have separately been negotiating with Tehran to reopen the Strait of Hormuz, a waterway that is vital to the global economy. It has been largely closed for nearly six months during the US-Iran war.

A reporter for Fox said the US president made the threat to Oman while using an expletive during a phone interview.

Earlier in the day, Iranian officials said they were close to finalising a deal with Oman. Meanwhile, the future of talks between the US and Iran is unclear as a 60-day Memorandum of Understanding (MoU) between the two sides is expiring.

Since the US and Israel attacked Iran in February, Tehran has largely blocked the Strait of Hormuz - through which about a fifth of the world's oil and liquefied natural gas usually passes. Reopening it has been a key point of discussion.

Oman borders the southern side of the Strait and says it is a neutral country in this conflict. However it has suffered a number of strikes from Iran and is now playing a key role in negotiating with Tehran to reopen the waterway.

Washington has pursued its own efforts to secure the reopening. Fox reporter Trey Yingst quoted Trump as saying: "If Oman gets in the way, we'll bomb the shit out of them."

During the same interview with Fox, Trump also said the US had a direct backchannel with the Islamic Revolutionary Guard Corps (IRGC), which is a major military, economic and political force in Iran.

An IRGC spokesman denied Trump's claim.

A spokesman told semi-official Iranian news agency Tasnim News: "There are no talks taking place between IRGC officials and the Americans, and this lie by Trump is merely fantasies caused by the delusions and nightmares he has suffered as a result of defeat and desperation in the war."