The British mercenary, Simon Mann, is set to go on trial in Equatorial Guinea accused of plotting a coup to overthrow the country's government in 2004. Mr Mann admitted involvement in the plot in March, although he said he was not the "main man" behind it. He could face the death penalty if convicted. The ex-SAS officer was arrested in Zimbabwe four years ago with 64 others. He served four years in prison there for trying to purchase weapons without a licence before being extradited. Eleven other men, including South African arms dealer Nick Du Toit who testified that he was recruited by Mr Mann, are already serving sentences in Equatorial Guinea in connection with the coup attempt. Du Toit also said he had been told they were trying to install an exiled opposition politician, Severo Moto, as president. Moto has been sentenced to a long prison term in absentia for his role. 'Co-operation' Last week, Public Prosecutor Jose Olo Obono said Mr Mann would face three charges when he goes on trial in Malabo - crimes against the head of state, crimes against the government and crimes against the peace and independence of the state. Mr Obono said Mr Mann could face the death penalty if convicted, but that it was unlikely the state would seek the maximum sentence. President Teodoro Obiang Nguema has told Channel 4 News that it would be up to the court to decide on the correct punishment. "We've reached a conclusion that Simon Mann was used as an instrument, but there were material and intellectual authors behind it that financed the operation," he said. President Obiang has accused the Spanish government, a former British cabinet minister whom he refuses to name, oil tycoon Eli Calil and Mr Moto, who lives in Spain, of involvement. Both named men have strongly denied any links to the plot. Mr Mann's lawyer, Jose Pablo Nvo, said he was working for his client "first, to not have a death sentence, and then to stay the least time possible in prison". 'Manager, not architect' The 55-year-old ex-Etonian, who has been held in Malabo's notorious Black Beach prison since being extradited in February, told Channel 4 News a month later that he had been the "manager, not the architect" of the plot to overthrow Mr Obiang. Mann went on to name those who were "part of the team", including Sir Mark Thatcher, the son of former UK Prime Minister Margaret Thatcher. Sir Mark was fined and received a suspended sentence in South Africa for his involvement in the coup. He has always claimed he was an unwitting conspirator and that, as far as he knew, he was helping finance a new company - an air ambulance business in West Africa. Equatorial Guinea, an oil-rich former Spanish colony, has been ruled by President Obiang since he seized power from his uncle in 1979. His government has been accused of widespread human rights abuses and of ruthlessly suppressing political opposition. Transparency International has put the tiny nation in its top 10 corrupt states. Source: BBC