Oil prices are climbing after US President Donald Trump refused to extend the ceasefire between the United States and Iran following its expiration on Monday.

Brent crude, the international benchmark for oil prices, broke above $91 per barrel as tensions persisted over the Strait of Hormuz and the potential for a return to conflict. The waterway is a crucial shipping route for global energy supplies, so any sign of disruption tends to feed quickly into oil markets and broader investor sentiment.

Speaking at the White House, Trump confirmed he would not seek to extend the 60-day memorandum of understanding between the two nations after it expired on Monday. The deal was originally touted as a key step on the road to peace.

The move followed Trump reiterating his ambition to make the Strait of Hormuz a US territory.

"It's a great idea. I mean, we control it with the blockade, and I like the idea of declaring it a territory," he said while taking questions at the White House last night.

"We have total control over the strait now. They [Iran] can be a nuisance, they can put a mine in the water, but the blockade has been very effective."

The comments came shortly after he turned his attention to Oman, which reached an agreement with Iran on the strait that runs between the two countries.

Iran's foreign affairs spokesperson Esmail Baghaei said an "understanding has been reached regarding the map of the transit route."

Trump, however, has threatened to "bomb the s**t" out of Oman if it "gets in the way" regarding the US negotiations.

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