The son of former Prime Minister Margaret Thatcher was a leader of a 2004 coup plot in oil-rich Equatorial Guinea that was backed by Spain and South Africa, according to a claim made in court.
Former special forces officer Simon Mann testified that Mr Thatcher was "not just an investor" in the plot to oust Equatorial Guinea President Teodoro Obiang Nguema Mbasogo, who has ruled the West African state since 1979.
Mr Mann, one of the defendants in the coup trial, identified Mr Thatcher as one of a five-man group headed by London-based Lebanese millionaire Eli Calil, whom he said masterminded and bankrolled the conspiracy.
"He (Thatcher) came on board completely and became part of the management team," Mr Mann told the court in the island capital.
He added Mr Thatcher invested some $350,000 in the March 2004 operation, which was foiled when authorities in Zimbabwe arrested Mr Mann and 70 mercenaries at Harare airport en route to Equatorial Guinea aboard a Boeing 727.
Public Prosecutor Jose Olo Obono said the next step after the trial, likely to end next week, was to seek the extradition of Mr Thatcher and Mr Calil. Both men deny involvement.
Mr Mann (56), said the governments of South Africa and former colonial power Spain knew and approved of the conspiracy to replace Mr Obiang with exiled opposition leader Severo Moto.
Spain's Foreign Ministry quickly issued a denial