The news came after Iran posted a video of Mr Akbari earlier this week showing what appeared to be forced confessions, and after the country's intelligence ministry had described the British-Iranian as "one of the most important agents of the British intelligence service in Iran".Human rights group Amnesty International called on the UK to investigate claims Mr Akbari was tortured before his death.Meanwhile, France summoned Iran's top diplomat in Paris over Mr Akbari's execution with its foreign ministry warning Iran's "repeated violations of international law cannot go unanswered"."Keeping the narrative of the West being involved is a way to maintain unity among the political establishment", she told BBC Radio 4's Today programme.'Tortured for 3,500 hours'In Mr Akbari's audio message he said that he was living abroad a few years ago when he was invited to visit Iran at the request of a top Iranian diplomat who was involved in nuclear talks with world powers."