The judiciary said Ali Reza Akbari, who was deputy defense minister until 2001, was a “key spy” for British intelligence, the semiofficial Tasnim news agency reported. It said Iranian intelligence unmasked the spying by feeding him false information.

Tasnim also reported that he had spied on past nuclear talks between Iran and Western powers. Akbari had served as deputy defense minister under President Mohammad Khatami, a reformist who had pushed for improved relations with the West.

Britain urged Iran to release Alireza Akbari on Wednesday.

“We are supporting the family of Mr. Akbari and have repeatedly raised his case with the Iranian authorities,” a British foreign office spokesperson said in a statement.

“Our priority is securing his immediate release and we have reiterated our request for urgent consular access.”

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 program. The killing of Iran’s top nuclear scientist in 2020, which Iran blamed on Israel, indicated foreign intelligence services had made major inroads.

Akbari, who ran a private think tank, has not been seen in public since 2019, when he was apparently arrested.

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.

Tasnim said the Supreme Court upheld his sentence and that he had access to an attorney. There was no word on when the execution might be carried out.

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.