THE trial of a Hampshire mercenary accused of plotting a coup in Equatorial Guinea got under way today.

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.

Mann, 55, who owns Inchmery House at Exbury, near Beaulieu, 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 amid tight security in Malabo, is Mann's first court appearance since his extradition.

A verdict is expected by Thursday.

A Foreign Office spokeswoman, speaking before the trial began, said: "We are offering consular assistance as we would with any British national detained overseas, and a representative will attend the beginning of the trial."

Equatorial Guinea's President Teodoro Obiang Nguema Mbasogo has not ruled out the death penalty.

He is reported to have said: "The tribunal will determine what kind of punishment Simon Mann will face.

"He's a criminal and we don't have relations with criminal bastards."

Mann is accused of "masterminding" the operation to oust President Obiang, according to a statement released by the Embassy of the Republic of Equatorial Guinea in Great Britain.

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.

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.

But the attorney-general of Equatorial Guinea, General Jose Olo Obono, said: "Simon Mann's trial will be free, fair and transparent.

"The trial is underpinned by our unshaken democratic principles and the untainted judgment of a free and independent country."

Asked if Mann would serve out any future sentence in the UK, President Obiang said: "It depends on the negotiations that we will have with the British Government because the criminal act happened here and the trial is taking place here.

"If the sentence is going to take place in another country, that's a matter of political negotiations with the British Government."

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.

Government-appointed defence 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".

Nvo will be the only one defending the Briton in court and took on the job just two weeks ago.

Equatorial Guinea held its first trial in the alleged plot in August 2004.

South African arms dealer Nick Du Toit was sentenced to 34 years in prison.

Mr Obiang's country is Africa's third biggest oil producer but many of its people remain poor.

The tiny nation is also considered to be among the continent's worst violators of human rights.