Simon Mann, the former SAS officer found guilty of plotting a coup in Equatorial Guinea, was thought to be heading home tonight after being freed from prison.

The 57-year-old mercenary leader's family expressed their delight that he was a free man for the first time since his arrest in Zimbabwe in 2004. He was released after serving less than two years of his 34 year sentence.

"Everyone is profoundly grateful to the President and the Government of Equatorial Guinea," the Manns said in a statement. "The whole family is overjoyed at the prospect of finally welcoming Simon home after five-and-a-half long years away."

Four other plotters - South African arms dealer Alan du Toit, who was also sentenced to 34 years, Sergio Cardoso, Jose Domingos and George Alerson were also pardoned and released.

President Teodoro Obiang Nguema granted the five men a full pardon for humanitarian reasons, said Supreme Court Chief Justice Obono Olo, the attorney general who prosecuted the coup plotters last year.

Judge Olo said Mann had wept when told he was being granted a pardon.

"I personally took him the legal papers he had to sign ahead of his release. He went red with emotion and his eyes filled with tears."

Earlier an official statement implied that ill health had triggered the release, saying that the plotters were being freed "with the hope that the accused return to their families and receive appropriate medical treatment according to their age and health", but Judge Olo appeared to contradict this, describing Mann as "fine, fit."

He confirmed that the five men had been freed today.

Mann is understood to have exchanged his prison cell for a five-star hotel in the capital Malabo where he had an emotional reunion with his sister and brother, Sarah and Edward. He is believed to be preparing to head for home, with his arrival in the UK thought to be scheduled for early tomorrow.

The deal for Mann's freedom was allegedly struck in two months of talks at the Ritz Hotel and the nearby Equatoguinean Embassy in London, which were kept secret from Mann's wife Amanda, according to a report in the Daily Mail. The Foreign Office was informed of the deal late last week by Equatorial Guinea's Ambassador.

Greg Wales, a businessman who was allegedly part of the coup plot, led the talks on Mann's behalf. He told the Mail: "In the two months of intense negotiations, I have found the Equatorial Guinea Government and Ambassador to be extremely reasonable, focused gentlemen of the highest integrity."

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