Washington (United States) (AFP) – President Donald Trump on Wednesday appeared to threaten to attack US ally Oman if it sides with Iran over reopening the Strait of Hormuz.

Trump said Oman must "behave" or he would "blow them up," when he was asked if he would accept a short-term deal to allow Iran and the Gulf state to control the waterway.

"No, the strait is going to be open to everybody," Trump told reporters during a cabinet meeting at the White House.

"It's international waters and Oman will behave just like everybody else or we'll have to blow them up. They understand that, they'll be fine."

The White House did not immediately respond when asked by AFP if Trump had misspoken and had intended to refer to Iran rather than Oman.

Oman is a key US ally which has tried to mediate the Middle East war and has itself come under attack from Tehran.

The US State Department later posted a clip and transcript of Trump's comments about Oman, without any correction or clarification.

The 79-year-old did earlier appear to mix up Iran and Venezuela, saying that the South American nation -- whose leader Nicolas Maduro was toppled by US forces in January -- "no longer has a navy, no longer has an air force."

Trump has repeatedly used such phrasing to refer to Iran, which the US and Israel attacked on February 28.

Iran has indicated that it seeks to impose a new reality in the Strait of Hormuz, through which one fifth of the world's oil normally passes, exacting tolls on transiting ships and sharing the revenues with Oman.

Trump has grown increasingly frustrated as talks to end the Middle East war and reopen the strait appear to have stalled once more, just days after he said a deal was near.