Iran has quadrupled its production of low-grade uranium enrichment amid increased tensions with the United States, nuclear officials have said.

Iranian officials stressed the uranium would only be enriched to the 3.67 per cent limit set by the 2015 nuclear deal, making it suitable for civilian nuclear power generation but well below the 90 per cent purity required to make atomic bombs.

However, by increasing production Iran will soon exceed the stockpile limit of 300kg.

“This is part of Iran’s pushback strategy against the Trump administration’s maximum pressure campaign,” Sanam Vakil, a Chatham House expert on Iran, told The Independent. “This is their effort at building up various portfolios that can then be used as leverage or bargaining positions if and when they come back to the negotiating table.”

Tehran has set a deadline of 7 July for Europe to set a new terms for the deal after US president Donald Trump withdrew from the deal.

It has warned it will enrich to medical grade levels of 20 per cent, closer to the 60 per cent needed for a dirty bomb or the 90 per cent for nuclear war head, if no deal is reached.

Revolution in Iran: In pictures Show all 11 1 /11 Revolution in Iran: In pictures Revolution in Iran: In pictures A demonstration against the Shah in 1979 Getty Revolution in Iran: In pictures Armed women on guard in one of the main squares in Tehran at the beginning of the Iranian Revolution Getty Revolution in Iran: In pictures Demonstrators hold a poster of Ayatollah Ruhollah Khomeini, in January 1979, in Tehran, during a demonstration against the Shah AFP/Getty Revolution in Iran: In pictures Iranian rebels pose with a U.S. flag they bayonetted upside down on trees at Sultanabad Garrison northeast of Tehran on February 12 2019 AP Revolution in Iran: In pictures A gun battle in Khorramshahr during the revolution, 1979 Getty Revolution in Iran: In pictures Ayatollah Khomeini's supporters demonstrate in the streets of Tehran against the Shah among tear gas. The "black friday" caused the death of 200 people according to the Iranian government, 2000 according to the opposition, September 8 1978 AFP/Getty Revolution in Iran: In pictures Women wearing the traditional Chador demonstrate in the streets of Tehran against the Shah on September 7 1978 AFP/Getty Revolution in Iran: In pictures Demonstrators in Tehran calling for the replacement of the Shah of Iran during the Iranian Revolution, 1979. They carry placards depicting Ayatollah Mahmoud Talaghani, one of the leading revolutionaries Getty Revolution in Iran: In pictures Ayatollah Khomeini's supporters demonstrate in the streets of Tehran against the Shah. The "black friday" caused the death of 200 people according to the Iranian government, 2000 according to the opposition, September 8 1978 AFP/Getty Revolution in Iran: In pictures Thousands of the Ayatollah Khomeini's supporters on the streets of Tehran calling for the religious leader's return in January 1979 Getty Revolution in Iran: In pictures The Iranian Islamic Republic Army demonstrates in solidarity with people in the street during the Iranian revolution. They are carrying posters of the Ayatollah Khomeini, the Iranian religious and political leader Getty

Ms Vakil said said Iran would probably breach the deal’s stockpile limit in 60 days, “sending a message” to Europe – and Russia and China – that its compliance “can’t be taken for granted anymore”.

Former US director of national intelligence James Clapper, speaking to the BBC, played down the uranium announcement, saying ”I don’t know that it’s necessary to go into the panic mode yet”.

He warned about the danger of accidental escalation, particularly as both US and Iranian vessels patrol in close proximity in the Strait of Hormuz.

“The thing I would be concerned about is some inadvertent incident that could go incendiary,” he said.

Tensions in the Middle East have flared after officials in the United Arab Emirates alleged four oil vessels including two Saudi Arabian oil tankers were sabotaged and Houthi rebels allied with Iran launched a drone attack on an oil pipeline in Saudi Arabia. Iran has denied it was behind any of the attacks.

The US has ordered B-51 bombers and an aircraft carrier to the Persian Gulf after warning of unspecified threats from Iran.

US president Donald Trump warned on Monday Iran would be met with “great force” if it attacked US interests in the Middle East, after a rocket landed near the US Embassy in the Green Zone of Iraq‘s capital Baghdad.

No one was reported injured in the rocket attack, which happened days after nonessential US staff were ordered to evacuate from diplomatic posts in the country.

Mr Trump told reporters: “I think Iran would be making a very big mistake if they did anything. If they do something, it will be met with great force but we have no indication that they will.”

The attacks all followed Mr Trump’s decision to attempt to cut off Iran’s oil exports, roughly a year after he withdrew from the 2015 nuclear accord between Iran and six major powers.

Iran Supreme leader Ayatollah Ali Khamenei says Iran is 'not seeking war with US'

Iranian president Hassan Rouhani rejected any talks with the US on Tuesday and called for the government to be given more power to run the sanctions-hit economy in an “economic war”.

“Today’s situation is not suitable for talks and our choice is resistance only” state news agency IRNA quoted Mr Rouhani as saying.

Iranian foreign minister Mohammad Javad Zarif criticised the US for sending its aircraft carrier and bombeer group to the region.

“Having all these military assets in a small area is in of itself prone to accidents,” he told CNN. “Extreme prudence is required and the United States is playing a very, very dangerous game.”

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Iraq will send send delegations to Washington and Tehran to help “halt tension” amid fears of a confrontation between the two powers in the Middle East, Iraqi prime minister Adel Abdul Mahdi announced on Tuesday.