Iran has executed British-Iranian national Alireza Akbari, the judiciary's Mizan news agency reported on Saturday, after sentencing him to death on charges of spying for Britain.

British Foreign Secretary James Cleverly said on Friday that Iran must not follow through with the execution of Akbari, a former Iranian deputy defence minister. Britain had described the death sentence as politically motivated and called for his immediate release.

"Alireza 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 in a tweet.

It accused him of receiving 1,805,000 euros, 265,000 pounds, and $50,000 for spying. In an audio recording broadcast by BBC Persian on Wednesday, Akbari said he had confessed to crimes he had not committed after extensive torture.

Iranian state media broadcast a video on Thursday that they said showed that Akbari played a role in the 2020 assassination of Iran's top nuclear scientist, Mohsen Fakhrizadeh, killed in a 2020 attack outside Tehran which authorities blamed at the time on Israel.

In the video, Akbari did not confess to involvement in the assassination but said a British agent had asked for information about Fakhrizadeh.

Iran's state media often airs purported confessions by suspects in politically charged cases. Reuters could not establish the authenticity of the state media video and audio, or when or where they were recorded.

Ties between London and Tehran have deteriorated in recent months as efforts have stalled to revive Iran's 2015 nuclear pact, to which Britain is a party.

Britain has also been critical of the Islamic Republic's violent crackdown on anti-government protests, sparked by the death in custody of a young Iranian-Kurdish woman in September.