LONDON - Former British prime minister Margaret Thatcher’s son became a spy for South Africa in a bid to avoid being prosecuted for his alleged involvement in a failed coup in Equatorial Guinea, a newspaper reported Sunday.

Sir Mark Thatcher has already been accused publicly by British mercenary Simon Mann, who was freed Nov 4 by the government of Equatorial Guinea after serving four years in jail for the 2004 coup attempt.

According to The Sunday Times report published Sunday, Thatcher met an intelligence official from the South African spy agency, SASS, while he was being investigated by police over allegations that he had helped finance the plot to overthrow the government of oil-rich country.

The report quoted a British journalist and writer as saying Thatcher told him he was accepted as an agent. But Thatcher was arrested just four days later by anti-corruption officers and charged under anti-mercenary laws.

Adam Roberts, a journalist with The Economist magazine and author of The Wonga Coup, a book about the plot, told the newspaper: Thatcher told me that four days before his arrest he had been accepted as an intelligence source by SASS. He blames his arrest on a lack of communication between various government departments.

Thatcher denies trying to strike a deal but the Equatorial Guinea government says it has evidence to show Thatcher and London-based Lebanese businessman Ely Calil were involved in the coup plot.