In eight short videos aired by state television after his execution, Mr. Akbari, dressed in suits, clean shaven and sitting in an office, detailed his spying activities and his recruitment by Britain at a function at the British Embassy in Tehran. But later, in an audio message broadcast by BBC Persian — it had been obtained through his family, according to Mr. Akbari’s brother — Mr. Akbari said the confessions were coerced.

The motivation for Mr. Akbari’s actions remain unclear. He said in the video that he was driven by “greed and power,” though also denied having financial problems. Iran says Mr. Akbari betrayed the country and traded state secrets for money. His family denies he was a spy and says that many assertions in the videos were fabricated by the Iranian government. But, they say, many of the dates and events in the videos were correct.

In the videos, Mr. Akbari said he was recruited in 2004 and told he and his family would be given visas for Britain. The next year, he traveled to Britain and met with an MI6 handler, he said. Over the next few years, Mr. Akbari said he created front companies in Austria, Spain and Britain to provide cover for meetings with his handlers. Iran has said that MI6 paid Mr. Akbari nearly 2 million pounds, currently about $2.4 million.

Mr. Akbari met with the British ambassador in Tehran as part of his official job, and traveled to Europe often for business, Mehdi Akbari said. He said that his brother, like many Iranian officials, had started branching out into various businesses while he was employed by the government, and that he was financially secure.