Donald Trump has announced an extension of the ceasefire until Iran submits a proposal to end the conflict permanently.

"Based on the fact that the Government of Iran is seriously fractured, not unexpectedly so and, upon the request of Field Marshal Asim Munir, and Prime Minister Shehbaz Sharif, of Pakistan, we have been asked to hold our Attack on the Country of Iran until such time as their leaders and representatives can come up with a unified proposal," he wrote on Truth Social.

He said he had directed the American military to "continue the Blockade and, in all other respects, remain ready and able".

The ceasefire was due to expire at 8pm on Wednesday US Eastern Time (10am, Thursday AEST).

Iran's Foreign Minister Abbas Araghchi said Tuesday that the US blockade of Iranian ports amounts to an "act of war" and constitutes a violation of the ceasefire.

In a post on X, Araghchi also said that "striking a commercial vessel and taking its crew hostage is an even greater violation."

"Iran knows how to neutralize restrictions, how to defend its interests, and how to resist bullying," he added.

Iranian foreign ministry spokesperson Esmaeil Baghaei says that Tehran's hesitation over participating in negotiations in Pakistan is not due to indecision, but what he described as conflicting signals and actions from the United States.

"The reason is not indecision; it is because of contradictory messages, contradictory behaviors, and unacceptable actions by the American side," Baghaei said, according to Iranian official media.

Baghaei said Iran would decide on taking part in negotiations "whenever they become results-oriented".

He also condemned US attacks on Iranian ships, calling them "a gross violation of international law," as well as "maritime piracy and state terrorism".

The conflict in the Middle East has triggered "the most severe energy crisis in a generation," UN Secretary-General António Guterres said on Tuesday, speaking remotely from New York to a climate conference in Berlin.

The current crisis, he said, makes it clear that "fossil fuels are not just wrecking our planet, they are holding economies hostage".

Guterres said that the energy crisis should be solved without exacerbating the climate crisis and that can be done by investing in homegrown renewables, developing the infrastructure to support them and providing financing for less developed economies to transition away from fossil fuels.

Transportation ministers from across the 27-nation European Union met in Brussels on Tuesday to discuss spiking energy prices because of the war in Iran, and how to protect consumers at home and at the pump after the head of the International Energy Agency warned that Europe has "maybe six weeks" jet fuel supplies remaining.

"This evolving geopolitical crisis in the Middle East has highlighted that Europe may have a short-term issue in supply of fuel," said Cyprus Transport Minister Alexis Vafeades, who is chairing the virtual meeting.

He said that there is currently no crisis, but that the bloc must prepare for the possibility of shortages.

"If this ever happens, it will affect connectivity, it will affect every citizen in the union," Vafeades said.

"We need to be ready to avoid queues at the gas stations if this ever happens."

China says that it hopes all parties can maintain the momentum for peace talks, as the two-week ceasefire in the Iran war is set to expire on Wednesday.

"The current situation is at a critical stage of transition between war and peace. At such a moment, it is all the more necessary for all parties to show the utmost sincerity, remain committed to a political solution, maintain the momentum of the ceasefire and negotiations," Chinese Foreign Affairs Ministry spokesman Guo Jiakun said.

Chinese President Xi Jinping called for the reopening of the Strait of Hormuz on Monday.

While it's not directly involved in ongoing mediation efforts, diplomats have said that China had pressed for Iran to attend the first round of negotiations.

Trump was responding to a question during a live telephone interview on Tuesday (Wednesday morning AEST) on CNBC, a business news network.

Asked if he would continue the ceasefire if there's progress in the next round of Iran talks, Trump said, "Well, I don't want to do that. We don't have that much time".

He said Iran "had a choice" and "they have to negotiate".

But it remained unclear when the ceasefire actually expires. Tuesday night was the deadline when the pause was announced two weeks ago, but Trump told Bloomberg News the ceasefire will expire Wednesday night.

Also during the Squawk Box appearance, Trump was asked directly if he'd resume strikes if there isn't progress in the coming talks in Islamabad.

"Well, I expect to be bombing because I think that's a better attitude to go in with," Trump said.

"But, you know, we're ready to go. I mean, the military is raring to go."

Hello and welcome to our rolling coverage of the war in the Middle East on Wednesday, April 22.

The two week ceasefire between the US and Iran is set to expire in the coming hours with question marks still hanging over whether this will be extended or not.

There are rumours the two countries will come back to Islamabad in Pakistan for further talks later today but neither side has confirmed these will be taking place as the countdown clock ticks on.

Regardless of whether the peace talks progress, Trump's indicated he's not keen to extend the fragile ceasefire.