Iran has executed a former Iranian deputy defense minister with dual British-Iranian nationality after convicting him of spying for the UK, the country's judiciary news agency, Mizan, reported on Saturday.

"Ali Reza Akbari, who was sentenced to death on charges of corruption on earth and extensive action against the country's internal and external security through espionage for the British government's intelligence service ... was executed," Mizan said.

Iran has one of the highest rates of execution in the world, with those sentenced to death being killed by hanging.

UK condemns execution, sanctions prosecutor general

Britain said it had imposed an asset freeze and travel ban on Iranian prosecutor general Mohammad Jafar Montazeri for "engaging in, providing support for and promoting serious human rights violations in Iran".

"The Prosecutor General is at the heart of Iran's use of the death penalty." British Foreign Secretary James Cleverly said. "We're holding the regime to account for its appalling human rights violations,"

British Foreign Minister Secretary James Cleverly called the execution a "barbaric act."

"This barbaric act deserves condemnation in the strongest possible terms. This will not stand unchallenged."

Cleverly also said Britain would temporarily withdraw its ambassador from Iran.

"It is important to recognize that our response are not necessarily limited to the actions that I've announced today," he said.

"I will decide obviously in consultation with my colleagues in government what further actions we may choose to take but I'm not going to speculate about those today," Cleverly added.

Earlier, British Prime Minister Rishi Sunak wrote on Twitter that he was "appalled by the execution" of Akbari.

"This was a callous and cowardly act, carried out by a barbaric regime with no respect for the human rights of their own people. My thoughts are with Alireza’s friends and family," he added.

The US ambassador to London said on Twitter that Washington condemned the execution.

"The execution of British-Iranian citizen Alireza Akbari in Iran is appalling and sickening," Ambassador Jane Hartley said. "The United States joins with the UK in condemning this barbaric act. My thoughts are with Alireza’s family."

What were the accusations against Akbari?

Iranian authorities claim that Akbari had worked for the UK's MI-6 intelligence agency and had held "extensive meetings with enemy intelligence officers in various countries over a long period of time," according to Mizan.

Iran said that Akbari had been involved in the 2020 killing of the country's top nuclear scientist Mohsen Fakhrizadeh. They also broadcast a video of Akbari confessing that he had been asked by a British agent about Fakhrizadeh.

But no evidence for the claims has been given. The BBC's Persian service broadcast an audio clip of Akbari on Wednesday in which he said he had confessed to crimes that he had not committed after being tortured.

Iranians who have dual citizenship, especially with the UK or US, are frequently arrested under espionage charges.

Iran's domestic problems

German Foreign Minister Annalena Baerbock joined the UK and the US in condemning the conviction and execution. 

"The charges against Ali Reza Akbari and his sentencing to execution were politically motivated. His execution would be unconscionable," US State Department spokesperson Vedant Patel 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.''

Tehran has blamed interference from foreign countries for the recent monthslong protests that have shaken the Islamic Republic and undermined the institution of rule by religious clerics.

It also comes at a low point for relations between Iran and the West following the breakdown of the Iran nuclear deal, the selection of hardline conservative Ebrahim Raisi as president, and Iran's role in supplying Russia with drones that have been used to attack Ukraine.

ab/wmr (Reuters, AP, AFP)