Guardian Unlimited

Agee quit the CIA in 1969 after 12 years in which he mainly worked in Latin America. He was later denounced as a traitor by George Bush Sr and was threatened with death by his former colleagues.

His famous 1975 book, Inside the Company: CIA Diary, cited alleged CIA misdeeds against leftwingers in the region and included a 22-page list of people he claimed were agency operatives.

Granma, Cuba's communist party newspaper, said Agee died on Monday night and described him as "a loyal friend of Cuba and fervent defender of the peoples' fight for a better world".

Bernie Dwyer, a journalist with state-run Radio Havana, said Agee had been in hospital since last month, where he died following several operations for perforated ulcers. Dwyer said friends planned a remembrance ceremony for him on Sunday at his Havana apartment.

In comments published last year, Agee defended his decision to expose the CIA: "It was a time in the 70s when the worst imaginable horrors were going on in Latin America.

"Argentina, Brazil, Chile, Uruguay, Paraguay, Guatemala, El Salvador - they were military dictatorships with death squads, all with the backing of the CIA and the US government. That was what motivated me to name all the names and work with journalists who were interested in knowing just who the CIA were in their countries."

His intent to destabilise the organisation by revealing the identities of CIA agents infuriated his former employers. In Britain, he worked with journalists to list the names of the agents, leading to many of them being sent back to Washington with their cover blown.

Agee wanted to settle in Cambridge with his partner, Angela, a leftwing Brazilian who had been jailed and tortured in her own country, and his two young sons by his estranged wife.

He planned to continue exposing the CIA but his plans were ruined when he was deported in 1978 as a threat to the security of the state.

He believes the US secretary of state, Henry Kissinger, urged the prime minister, Jim Callaghan, to act because of a belief that Agee had disrupted the Jamaican elections in favour of leftwinger Michael Manley by exposing CIA activities there.

He settled in Germany with his new lover, a ballet dancer called Giselle Roberge, and later split his time between Hamburg and Havana. In 1979, his US passport was finally revoked and was never returned.

However, Agee had no regrets about his decision to blow the whistle on the CIA. He said: "There was a price to pay. It disrupted the education of my children [Phil and Chris, then teenagers] and I don't think it was a happy period for them. It also cost me all my money. Everything I made from the book, I had to spend.

"But it made me a stronger person in many ways and it ensured I would never lose interest or go back in the other direction politically. The more they did these dirty things, the more they made me realise what I was doing was important."

Under the US Freedom of Information Act, Agee was able to discover the CIA had accumulated 18,000 pages of information on him.

Agee was repeatedly blamed for the death of Richard Welch, the CIA station chief in Athens who was assassinated in 1975.

"George Bush's father [George Bush Sr] came in as CIA director in the month after the assassination and he intensified the campaign, spreading the lie that I was the cause of the assassination. His wife, Barbara, published her memoirs and she repeated the same lie, and this time I sued and won, in the sense that she was required to send me a letter in which she apologised and recognised what she wrote about me was false.

"They've tried to make this story stick for years. I never know what government hand or neocon hand is behind the allegations, and I don't pay too much attention, but I know I haven't been forgotten."

Agee was a great supporter of what he regarded as Cuba's progressive policies providing universal healthcare and education, and he regarded the current US president as the "antithesis" of those achievements.

Writing in the Guardian last year, he said: "All Cuba's achievements have been in defiance of US efforts to isolate Cuba. Every dirty method has been used, including infiltration, sabotage, terrorism, assassination, economic and biological warfare and incessant lies in the media of many countries."

Agee denied claims from a former Cuban intelligence officer he had received $1m from Cuban intelligence.

Despite the long-running bitterness between him and the US authorities, Agee was allowed to return to the US many times without being arrested and was allowed back into Britain under John Major's government.

In the 1990s, he set up a company to bring visitors to Cuba. Many travellers came from the US, even though Americans are forbidden by law from visiting the country and can be fined heavily if caught.