IRAN’S foreign minister has warned that any attack on his country over a drone and missile strike on Saudi Arabia’s oil industry will result in “all-out war”, further increasing tensions across the Persian Gulf.

The comments by Mohammad Javad Zarif represent the starkest warning offered yet by Iran in a long summer of mysterious attacks and incidents following the collapse of Iran’s nuclear deal with world powers, more than a year after US President Donald Trump unilaterally withdrew America from the accord.

Zarif’s comments also appeared to be in response to US secretary of state Mike Pompeo, who a day earlier while travelling to Saudi Arabia referred to the attack as an “act of war”.

Asked by CNN what would be the consequence of a US or Saudi strike, Zarif said: “All-out war.”

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It would cause “a lot of casualties”, he stressed.

“I am making a very serious statement that we don’t want to engage in a military confrontation. But we won’t blink to defend our territory.”

He added that any sanctions placed by the US on Iran after pulling out of the nuclear deal would need to be lifted before any further negotiations could be considered.

“They’ve done whatever they could and they haven’t been able to bring us to our knees,” Zarif said.

Pompeo has now arrived in the United Arab Emirates.

America’s top diplomat met earlier yesterday with Saudi Crown Prince Mohammed bin Salman in Jeddah over Saturday’s attack on a crucial oil processing facility and oil field, which halved the kingdom’s oil production.

Yemen’s Iranian-backed Houthi rebels have claimed the attack, but the US alleges Iran carried out the assault.

“The US stands with #SaudiArabia and supports its right to defend itself,” Pompeo tweeted. “The Iranian regime’s threatening behaviour will not be tolerated.”

Pompeo did not elaborate. President Trump has been noncommittal on whether he would order US military retaliation.

He separately said on Wednesday that he is moving to increase financial sanctions on Tehran over the attack, without elaborating. Iran already is subject to a crushing American sanctions programme targeting its crucial oil industry.

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Pompeo met Abu Dhabi’s powerful crown prince, Sheikh Mohammed bin Zayed Al Nahyan. The UAE is a close ally of Saudi Arabia and joined the kingdom in its war in Yemen against the Houthis.

The UAE announced yesterday it had joined a US-led coalition to protect waterways across the Middle East after an attack on Saudi oil installations.

The state-run WAM news agency quoted Salem al-Zaabi, of the Emirati Foreign Ministry, as saying the UAE joined the coalition to “ensure global energy security and the continued flow of energy supplies to the global economy”.

Saudi Arabia joined the coalition on Wednesday. Australia, Bahrain and the UK are also taking part.

Pompeo tweeted his appreciation for the UAE and Saudi Arabia joining the coalition.

“Recent events underscore the importance of protecting global commerce and freedom of navigation,” he wrote.

The US formed the coalition after attacks on oil tankers that American officials blame on Iran, as well as Iran’s seizure of tankers in the region.

Iran denies being behind the tanker explosions, though the attacks came after Tehran threatened to stop oil exports from the Persian Gulf.

At a press conference on Wednesday, the Saudis displayed broken and burned drones and pieces of a cruise missile that military spokesman Colonel Turki Al-Malki identified as Iranian weapons collected after the attack.

He also played surveillance video that he said showed a drone coming in from the north. Yemen is to the south of Saudi Arabia.

Eighteen drones and seven cruise missiles were launched in the assault, he said, with three missiles failing to make their targets. He said the cruise missiles had a range of 435 miles, meaning they could not have been fired from inside Yemen.