United States President Donald Trump has warned that an Iranian proposal to bring an end to the war is not enough to avert his threat to destroy infrastructure unless Tehran reopens the Strait of Hormuz.

Trump said on Monday that the Tuesday deadline he has set for Iran to make a deal was final. Amid a rash of additional threats and claims, he said the proposal would not alleviate US action.

“It’s a significant proposal. It’s a significant step. It’s not good enough, but it’s a very significant step,” Trump told reporters at the White House, adding that intermediaries “are negotiating now”.

Trump warned on Sunday that unless Tehran agreed by Tuesday evening to allow free passage of ships through the Strait of Hormuz, he would order strikes on Iran’s power plants and bridges.

In peacetime, about 20 percent of the world’s oil supplies pass through the strategic waterway, which links the Gulf to the Indian Ocean.

Earlier on Monday, a 45-day ceasefire proposal was put forward by Pakistan after meetings seeking a diplomatic solution to the war, which was sparked on February 28 by Israeli and US attacks against Iran, which has responded by firing missiles at targets across the Middle East.

Iran’s state-run IRNA news agency said Tehran had conveyed its response via Islamabad. Iran reportedly rejected the proposed truce, putting forward instead a call for a permanent end to the hostilities.

The Iranian proposal consisted of 10 clauses, including an end to conflicts in the region, a protocol for safe passage through the Strait of Hormuz, the lifting of sanctions and reconstruction, IRNA added.

“We won’t merely accept a ceasefire,” Mojtaba Ferdousi Pour, the head of Iran’s diplomatic mission in Cairo, told The Associated Press news agency. “We only accept an end of the war with guarantees that we won’t be attacked again.”

‘Animals’

The White House confirmed that the ceasefire proposal was under consideration but Trump had “not signed off” on it and the war was continuing.

“This is one of many ideas, and POTUS [the president of the United States] has not signed off on it. Operation Epic Fury continues,” a White House official told the AFP news agency.

Later, Trump said he was “highly unlikely” to postpone the deadline from 8pm Washington time on Tuesday (00:00 GMT). “They’ve had plenty of time,” he said.

Trump has warned that the US could bomb Iran “back to the stone ages” unless it agrees a deal.

Asked if he was concerned about suggestions that attacks on infrastructure are classified as a war crime, he retorted: “I’m not worried about it.”

“You know the war crime?” he continued. “The war crime is allowing Iran to have a nuclear weapon,” adding that Iran’s leaders are “animals” who have  killed tens of thousands of protesters.

Economic linchpin

Iran’s rejection of the ceasefire proposal came as Israel struck a key petrochemical plant for the South Pars gasfield and killed two commanders of the Islamic Revolutionary Guard Corps.

Israel claimed responsibility for the strikes on the plant in Asaluyeh, a key site for Iran’s energy sector and its wider economy, both for production of petroleum by-products and for joint work with Qatar on the world’s largest natural gasfield. The strike appeared to be separate from Trump’s threats and deadline.

Iran’s grip on the strait has caused oil prices to surge and shaken the world economy.

The National Petrochemical Company said the situation was “under control” after the strike with the extent of the damage being assessed.

“A fire has been brought under control. The situation is currently under control, and technical aspects, as well as the extent of the damage, are under investigation,” IRNA cited the petroleum company as saying, adding that no injuries had been reported.

The White House did not immediately comment on the attack.

After an Israeli attack on South Pars in March, Trump said Israel would not attack it again but warned that if Iran continued striking Qatar’s energy infrastructure, the US would “massively blow up” the field.