An Iranian-British dual national sentenced to be hanged for spying for UK intelligence once held roles at the top of Tehran's defence and security establishment, Iran's state media said Thursday.

Alireza Akbari held posts including "deputy minister of defence for foreign affairs" and was in the "secretariat of the Supreme National Security Council", state news agency IRNA reported.

Akbari had also been an "advisor to the commander of the navy" as well as "heading a division at the defence ministry's research centre", it added.

Akbari was found guilty of "corruption on earth and for harming the country's internal and external security by passing on intelligence," the judiciary's Mizan Online news agency reported Wednesday.

Britain has demanded Tehran halt what foreign minister James Cleverly has called a "politically motivated" execution.

Mizan, citing a statement from Iran's intelligence ministry, said Akbari became a "key spy" for Britain's Secret Intelligence Service, more commonly known as MI6, due to "the importance of his position".

In February 2019, the official government newspaper Iran published an interview with Akbari, whom it identified as a "former deputy defence minister" during the 1997-2005 presidency of Mohammad Khatami.

IRNA, which said Akbari is aged 61 and is a veteran of the Iran-Iraq war that raged from 1980-1988, said he was arrested sometime between March 2019 and March 2020.

The state news agency also published a nine-minute video showing pictures of Akbari, including with people with their faces concealed.

In the video, he is seen apparently talking about his contacts with Britain, and also says he was questioned by the British about Iran's top nuclear scientist Mohsen Fakhrizadeh, assassinated in November 2020 in an attack that Tehran blames on arch-foe Israel.

In early December, Iran executed four people accused of working with Israeli intelligence, Mizan said at the time.

Iran hanged them four days after the Supreme Court upheld their death sentence for "their intelligence cooperation with the Zionist regime (Israel) and kidnapping", Mizan reported.