Mann, a former Old Etonian and SAS officer, was last week revealed to be suffering multiple organ failure in his cell in the Zimbabwe capital, Harare.
He is also said to be going blind, and has a life-threatening intestinal condition caused by poor diet. The 53-year-old “security consultant”, originally from Hampshire, is serving a seven-year sentence for his part in an attempt to oust another dictator, Teodor Obiang Nguema, head of Zimbabwe’s neighbour, Equatorial Guinea.
Last night Amnesty International said it was monitoring Mann’s condition and attempting to obtain further information.
Mann has admitted being involved in the arms trade in Africa, but always denied his alleged part in the foiled coup.
He has maintained that weapons found in his possession at Harare airport in
2004 were destined for a private company guarding diamond mines in the Democratic Republic of Congo. The mercenary has also maintained that any confession he made was beaten out of him.
Sir Mark, an old school friend, was convicted in 2005 by a court in South Africa, which ruled that he had helped finance the coup attempt. Thatcher also denied any involvement, but was given a suspended four-year prison sentence and fined £265,000.
Mugabe is believed to have been planning to hand Mann over to Equatorial Guinea in exchange for oil. The tiny former Spanish colony is Africa’s third largest producer and poverty-stricken Zimbabwe is in desperate need of fuel.
Mann has not been able to attend two successive court sessions after being admitted to hospital at the Chikurubi maximum security prison.
His lawyer, Jonathan Samkange, said his client is awaiting major surgery because of his deteriorating health.
“We have applied to the minister of justice for the second time to have my client treated at a private hospital but that has been unsuccessful,” he said.
“Simon Mann is suffering from multiple organ failure and he needs a major operation to recoup. His sight needs a check-up, he has developed scabies, and his digestive system has always been upset.”
Explaining Mann’s deteriorating health, Mr Samkange said the mercenary was tortured in a bid to force him to reveal his coup plan.
“I have requested the court to investigate the findings that Mann had been tortured in the run-up to the extradition hearings to force a pre-determined outcome to the process. I am happy the prosecution has accepted my application,” he said. Mr Samkange was part of the group of human rights lawyers that visited the country’s prisons in March.
According to prison sources, Zimbabwe police assaulted and tortured Mann during a special interrogation in the presence of officials from Equatorial Guinea who had requested to see him as evidence that he is still in prison.
Mr Samkange said: “My client was severely tortured by members of the military intelligence and Central Intelligence Organisation operatives in prison. The prison authorities have not denied that Mann was tortured during unscheduled visits by state security agents.”
He added: “Simon Mann has already been tortured here in prison and we will not have him extradited to Equatorial Guinea for further torture.
“He has been tortured at the request of a country applying to have him tried under its jurisdiction.” Mr Samkange vowed to resist efforts outside the law that the West African country was pursuing to win Mann’s extradition.
A Harare court will resume extradition hearings on Friday and the prosecution has promised to bring Mann to court this time. He is due to be released on May 11.
The Zimbabwe Lawyers for Human Rights, which has been on a fact-finding mission to the prison, confirmed Mr Samkange’s claims.
The organisation reported: “Simon Mann is very sick and is still awaiting permission to have a complicated operation that is beyond the capacity of Chikurubi prison hospital.”
Another European implicated in the coup attempt, a former German soldier, died in mysterious circumstances soon after his arrest. He too was allegedly tortured.
Neil Durkin, spokesman for Amnesty International, said: “If it is indeed true that he has been tortured in detention, it would be yet another appalling example of gross human rights violations in President Mugabe’s Zimbabwe.”
Mann’s wife Amanda was last night on holiday in Spain with their three children.
A family friend in the village of Exbury, on the edge of the New Forest, said: “We didn’t know anything about this, but we are not surprised, given what they do in these places. We just hope it’s not that bad.”
Sir Mark Thatcher was last night unavailable for comment at his home in London’s Belgravia.
