Simon Mann, the Old Etonian mercenary accused of plotting a coup against the president of Equatorial Guinea in 2004, will stand trial in the tiny oil-rich West African nation tomorrow amid signals that the legal process has been rigged against him.

Mann’s Equatoguinean defence lawyer Ponciano Mbomio Nvo was unceremoniously stripped of his right to practice in the country last week — coinciding with a sudden announcement that the trial was about to begin.

Mr Mbomio Nvó has been replaced by José Pablo Nvó, a lawyer who has been described as being a supporter of President Obiang’s ruling political party.

Mr Mbomio Nvó told The Times last week that it was impossible for Mann’s trial to begin any time soon because the correct legal procedures, based on the Spanish judicial system, have not been observed.

He said that the preparation of the case was still at the police stage and that the defence had not even been informed of the specific charges that Mann faces.

Since Mann was extradited from Zimbabwe in January, where he served a three-year prison sentence for immigration irregularities, Mr Mbomio Nvó has been building a case based around the former mercenary’s illegal extradition.

No extradition treaty existed at the time that Mann was flown out of Zimbabwe to the notorious Black Neach prison in Malabo, the capital of Equatorial Guinea. His defence lawyers launched an immediate appeal against the decision to extradite him, but Mann went missing for three days during the legal wrangle and only resurfaced once he was in Equatoguinean custody.

By the middle of last week Mr Mbomio Nvó had still heard nothing from the state prosecutor’s office nor seen any of the evidence against his client. Under the Spanish system of examining magistrates, both the prosecution and defence are given several weeks to examine the files before a trial begins.

In April Mr Mbomio Nvó was accused of defamation by Equatoguinean attorney general José Oló Obono — a man whom Mr Mbomio Nvó has defended in the past and whose release he secured from Black Beach prison.

At the time Mr Mbomio Nvó said he was not alarmed nor surprised by the development and continued to practice as the country’s only independent lawyer.

However, the coincidence of the announcement of the start date for Mann’s trial and Mr Mbomio Nvó’s suspension for a year by the country’s College of Lawyers will raise suspicions that the Old Etonian and former friend of Mark Thatcher will not be fair.

Amnesty International claimed that the 2004 trial of Mann’s co-accused conspirators, including Nick du Toit, was similarly flawed.

Mann, a former officer in the SAS, was arrested in 2004 with 70 other men when his plane landed in Zimbabwe to collect a shipment of arms purchased from the country’s state arms manufacturer.

Another group, which included du Toit, was arrested in Equatorial Guinea itself. Together they were accused of hatching a plot to overthrow the country’s president, who seized power in a coup in 1979.

Although Mann “confessed” in a television interview that he was the “manager” of the plot, he denied he was the “main man”. He implicated Mr Thatcher, son of the former prime minister Margaret Thatcher, as part of the conspiracy. The Equatoguineans have issued an international arrest warrant for Mr Thatcher through Interpol.

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