Iran said on Saturday it had executed a dual Iranian-British national who once worked for its defence ministry, despite an international outcry over his death sentence and those of others held amid nationwide protests.

Iran’s Mizan news agency, associated with the country’s judiciary, announced Ali Reza Akbari’s hanging.

It did not say when it happened. However, there were rumours he had been executed days ago.

Iran had accused Akbari, without offering evidence, of being a spy for Britain’s MI6 intelligence agency. It aired a highly edited video of Akbari discussing the allegations resembling others that activists have described as coerced confessions.

On Friday, State Department deputy spokesman Vedant Patel criticised Akbari’s pending execution.

”The charges against Ali Reza Akbari and his sentencing to execution were politically motivated. His execution would be unconscionable,” he said. “We are greatly disturbed by the reports that Mr Akbari was drugged, tortured while in custody, interrogated for thousands of hours, and forced to make false confessions.”

He added: “More broadly, Iran’s practices of arbitrary and unjust detentions, forced confessions, and politically motivated executions are completely unacceptable and must end.”

Britain’s Foreign Office did not immediately respond to a request for comment.

Foreign Secretary James Cleverly had earlier called on Iran to stop the execution.

”The Iranian regime should be in no doubt,” he wrote Friday online. “We are watching the case of Ali Reza Akbari closely.”

Iran’s government for months has been trying to allege - without offering evidence - that foreign countries have fomented the unrest gripping the Islamic Republic since the death of a woman in September detained by the morality police. Protesters say they are angry over the collapse of the economy, heavy-handed policing and the entrenched power of the country’s Islamic clergy.

Iran is one of the world’s top executioners.

For several years, Iran has been locked in a shadow war with the United States and Israel, marked by covert attacks on its disputed nuclear programme. The killing of Iran’s top nuclear scientist in 2020, which Iran blamed on Israel, indicated foreign intelligence services had made major inroads.

Iranians protest the death of 22-year-old Mahsa Amini after she was detained by the morality police last month, in Tehran in October. Photo / AP

Akbari, who ran a private think tank, has not been seen in public since 2019, when he was apparently arrested. He also was close to Ali Shamkhani, a top security official in Iran, leading analysts to suggest his death sentence was tied to a possible power struggle within the country’s security apparatus amid the protests.

Akbari had previously led the implementation of a 1988 cease-fire between Iran and Iraq following their devastating eight-year war, working closely with UN observers.

Authorities have not released any details about his trial. Those accused of espionage and other crimes related to national security are usually tried behind closed doors, where rights groups say they do not choose their own lawyers and are not allowed to see evidence against them.

The anti-government protests, which have continued for nearly four months with no sign of ending, are one of the biggest challenges to the Islamic Republic since the 1979 revolution that brought it to power.

At least 520 protesters have been killed and more than 19,300 people have been arrested, according to Human Rights Activists in Iran, a group that has been monitoring the unrest. Iranian authorities have not provided official figures on deaths or arrests.

Iran has executed four people after convicting them of charges linked to the protests in similarly criticized trials, including attacks on security forces.