A Zimbabwe court has begun hearing an application to have the British leader of a group of alleged mercenaries extradited to Equatorial Guinea.
Mann is due to be released in May on good behaviour
Simon Mann is accused of being the mastermind of a plot to overthrow Equatorial Guinea's president in 2004.
The former SAS officer was arrested and jailed in Zimbabwe for apparently trying to buy arms as part of the plot.
His lawyer argued the request should be turned down, as he would not receive a fair trail and could face torture.
Mann, who is serving a four-year prison term in Zimbabwe for buying weapons without a licence, is due to be released in May for good behaviour, Reuters news agency reports.
"Because this case is political, he [Mann] will not get a fair trial and he will be severely tortured," Mann's lawyer Jonathan Samkange told the court.
Twenty-three suspected mercenaries have already been convicted in Equatorial Guinea in connection with the coup plot.
"Others facing the same charges have not received a fair trial, one has died from torture," he said.
But in a written request to the court, Equatorial Guinea's attorney general said it was important that Mann answer questions in connection with the conspiracy.
"Simon Mann is the intellectual head of the mercenary operation and coup plot. He is the key person who planned and led this operation," AFP news agency quotes Jose Olo Obono as saying.
The lawyer representing the oil-rich state said there was enough evidence to show Mann had a "legal case to answer".
"The applicant has also given assurances that the death sentence will not be pursued if Mr Mann is convicted, and that he will get a fair trial," Joseph Jagada said, Reuters reports.
Mr Samkange said his client, who did not appear in court on Thursday, was ill and was due to have an unspecified operation soon.
But he said Mann was expected to give evidence at later proceedings.
Mr Mann was arrested in March 2004 for allegedly purchasing weapons in Zimbabwe for the planned coup attempt.
More than 60 men arrested with him - most of them South African citizens of Angolan origin - were released in 2005 after serving a year's sentence in Zimbabwe.
They flew to Zimbabwe from South Africa to pick up the weapons and were allegedly on their way to Equatorial Guinea to meet another group involved in the plot, when both groups were arrested.
Sir Mark Thatcher, son of former UK Prime Minister now Baroness Thatcher, was fined and received a suspended sentence in South Africa for his involvement in the affair.
The relatives of those being held in Equatorial Guinea have complained of abuse and unfair treatment.
One suspect, a German, died in prison after what Amnesty International said was torture.
Equatorial Guinea, a former Spanish colony, has been ruled by President Teodoro Obiang Nguema since he seized power from his uncle in a coup in 1979.