Equatorial Guinea pardoned Mann this week on health grounds after he had served just over one year of a 34-year sentence for a 2004 coup attempt on the oil-producing nation that was foiled when he was arrested in Zimbabwe.

"He has left on a private jet," an airport official told Reuters on Wednesday morning, adding that Mann’s brother and sister were with him on the plane.

The official could not confirm where the jet was headed but a second official at air traffic control at Malabo airport said a Falcon 900 private jet that took off around the same time was headed for London.

Mann’s pardon by President Teodoro Obiang Nguema Mbasogo comes just weeks before an election in which Obiang is expected to seek and win a new mandate to lead sub-Saharan Africa’s third largest oil producer, which he has governed since 1979.

Analysts and diplomats have said that Obiang had little to gain from holding Mann any longer and the move was likely to be aimed at improving his image. Obiang has drawn criticism for rights abuses and the mismanagement of vast oil riches.

"I am very grateful to President Obiang, who has been very generous with us," Mann said during his last court hearing on Tuesday, according to a statement posted on the Equatoguinean government’s website www.guineaecuatorialpress.com/.

Mann, who spent over three years in prison in Zimbabwe before being extradited to Equatorial Guinea last year, said he had been treated more like a guest than a prisoner and thanked the president for paying for two hernia operations he needed.

"Now I am relieved that the coup d’etat we tried to lead in 2004 was not successful," Mann was quoted as saying.  

Four of Mann’s accomplices, including South African Nick du Toit, were also pardoned this week. South Africa in a statement welcomed the release of four of its nationals.

Their release coincides with South African President Jacob Zuma’s visit to the tiny central African nation.