Simon Mann's defence lawyer had argued he was "a pawn" in the plot
Former British soldier Simon Mann, who had been sentenced to 34 years for a coup plot in Equatorial Guinea, has been freed.
Earlier Mann and four South Africans jailed with him had been pardoned by the country's president and were told to leave within 24 hours.
Mann, who was sentenced in July 2008, had admitted to conspiring to oust President Teodoro Obiang Nguema.
Mann's family said they were "absolutely delighted".
Equatorial Guinea's ambassador to the UK Agustin Nze Nfumu told the BBC World Service's Focus on Africa programme that Mann was now with his brother and sister who had travelled to the country for his release.
"He's in [the capital] Malabo with his family," he said. "The family took a private plane for him and they are waiting and they will decide when to leave the country."
A Mann family statement said: "Everyone is profoundly grateful to the president and the government of Equatorial Guinea.
"The whole family is overjoyed at the prospect of finally welcoming Simon home after five-and-a-half long years away."
'Live in peace'
An adviser to President Obiang, Miguel Mifuno, said that Mann, 57, had been released on humanitarian grounds related to his health. Mann had a hernia operation in 2008.
Frank Gardner, security correspondent, BBC News
No-one could accuse Simon Mann of seeking the quiet life. The son of an England cricket captain, educated at Eton and Sandhurst, he went on to serve in the Scots Guards and passed the British Army's most rigorous selection test to get into the SAS.
After leaving the Army he co-founded Sandline International, a private security firm that got involved in Sierra Leone's civil war. In 2004 his world fell apart. After his arrest in Zimbabwe, he was tried, sentenced and spent four hellish years in prison.
Last year, after another trial in Equatorial Guinea, he was jailed for 34 years. But his cooperation with the authorities, and his naming of alleged accomplices, including Sir Mark Thatcher, appear to have helped win him this sudden and unexpected pardon.
Mr Mifuno said: "Simon Mann conducted himself in exemplary fashion during his trial and his incarceration in Equatorial Guinea.
"He has had some health problems, and was operated on. He is now in good health but the president thinks he should now be allowed to live in peace with his family."
Mr Mifuno told BBC News that the releases were timed to coincide with a visit to Equatorial Guinea by South African President Jacob Zuma.
The Foreign Office said it understood it was a personal decision by the president on humanitarian grounds.
Equatorial Guinea's Supreme Court judge had earlier told the BBC that Mann would be leaving jail on Tuesday.
Justice Obono Olo also said he had met Mann in the past few days and that he was "in good health".
BBC Africa bureaux editor, Sara Halfpenny, says Mann is very unlikely to travel to Johannesburg as he runs the risk of being arrested under the South Africa Mercenary Act.
She adds that Scotland Yard wants to talk to Mann about the possible involvement of London-based millionaire Ely Calil and Sir Mark Thatcher, son of UK former Prime Minister Margaret Thatcher, in the coup.
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Sources in Scotland Yard's Counter Terrorism Command have confirmed to the BBC that there is an ongoing investigation into whether any offences relating to the coup were committed in the UK.
BBC security correspondent Frank Gardner says Mann's release has been a surprise and that Mann's family had only been told 24 hours ago.
"He's going to see a son he's never seen, who was born when he was in prison. This is a man, who if he had served his whole sentence, would have come out in his 90s," our correspondent says.
Equatorial Guinea analyst Antony Goldman told the BBC that friends of Mann had been hinting of his possible release for several weeks.
But he said that the timing of the move - three weeks ahead of presidential elections - was something of a surprise in a country where officials constantly feared that concessions could be interpreted as weakness.
Some analysts had suggested that Mann was released because he posed a security risk, but Equatorial Guinea's ambassador rejected this.
"Tell those people that they are writing novels, if they want to make another movie on that let them invent stories," Mr Nze Nfumu said. "The man has been there almost two years, I don't know what security risk - I can't commend such nonsense."
In March 2004, Mann and 63 others were arrested in Zimbabwe on board a plane that arrived from South Africa. Its destination was Equatorial Guinea.
His extradition came after he had served four years in prison in Zimbabwe for trying to purchase weapons without a licence.
Equatorial Guinea, an oil-rich former Spanish colony, has been ruled by President Obiang since he seized power from his uncle in 1979.
Mann's lawyer had asked for leniency, saying his client was a pawn of powerful international businessmen and had been "not a co-author" of the coup plot but "an accomplice".
The former special forces officer apologised, saying he was not the most senior coup plotter.
Mann had implicated Sir Mark Thatcher and Lebanese businessman Ely Calil as organisers of the plot.
Sir Mark, who now lives in southern Spain, was fined and received a suspended sentence in South Africa in 2005 for unknowingly helping to finance the plot.
After Mann's verdict, Sir Mark reiterated to the BBC that he had had no direct involvement.
He said he had known nothing about any plan to overthrow the government and added that he had already faced justice in South Africa.
Upon Mann's release, Sir Mark released a statement, saying: "I am delighted that Simon will be reunited with his family at last."
Mr Calil also said he was "thrilled" at the news, adding: "I'm sure that friends who have been praying for his safe return since this nightmare began will rally around."
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