A British mercenary accused of plotting a coup in Equatorial Guinea has gone on trial.

Former SAS officer Simon Mann is alleged to have been the leader of a group who planned to overthrow the West African government in 2004.

The 55-year-old is being held in the notorious Black Beach prison in the capital Malabo, after being extradited secretly from Zimbabwe in February.

The trial, which opened amidst tight security in Malabo, is Mann's first court appearance since his extradition. A verdict is expected by Thursday.

Equatorial Guinea's state prosecutor has asked the court to jail the accused for nearly 32 years.

But Mann's lawyer, Jose Pablo Nuo, said his client was a "mere instrument" in the coup and not one of the principal organisers.

He is accused of "masterminding" the operation to oust Mr Obiang, according to a statement released by the Embassy of the Republic of Equatorial Guinea in the UK.

Mann, an old Etonian, was originally arrested with around 70 other people, mostly former soldiers, when their aircraft arrived at an airport in the Zimbabwean capital, Harare, in March 2004.

They had come to collect weapons bought from the Zimbabwe state arms maker, and insisted they were on their way to guard mining facilities in the Congo, even though they were found with uniforms identical to those of President Obiang's presidential guard.

Mark Thatcher, the son of former prime minister Baroness Thatcher, was given a suspended sentence in South Africa in relation to the funding of Mann's operation, though he has always denied any knowledge that a coup was being plotted.

In March, Mann admitted involvement in the conspiracy, but insisted he was not the "main man" behind the operation.

In an interview from inside Black Beach prison, he said: "It was a mistake and I have to carry the can for that. I blame myself most for simply not saying 'cut' two months before we were arrested."

He added: "I was involved. I was, if you like, the manager - not the architect, and not the main man..."

Officials from Equatorial Guinea have said that Mann will receive a "free, fair and transparent" trial.

Following his extradition, Mann's wife, Amanda, attacked Equatorial Guinea for "kidnapping" him, saying his detention was "monstrous" and she feared for his well-being.

President Obiang has ruled the country since 1979, when he seized power in a military coup and, though nominally a democracy, presidential elections in 1991, 1996 and 2002 were widely seen as flawed.

In recent years the country has experienced rapid economic growth following the discovery of large offshore oil reserves, and is now one of Africa's largest exporters.

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