Nairobi/Malabo  - One of the South African mercenaries released along with British coup plotter Simon Mann from a prison in Equatorial Guinea revealed Wednesday his country's President Jacob Zuma was pivotal in securing the pardons.

Speaking to South Africa's The Star newspaper after his release from Equatorial Guinea's notorious Black Beach prison Nick Du Toit said the prisoners were told that "Zuma and his government were involved in the negotiations for our release."

Equatorial Guinea's President Teodoro Obiang Nguema, whom the men sought to overthrow, pardoned Mann, Du Toit and three other South Africans hours before Zuma flew into the tiny oil-rich west African state on a one-day visit.

Nguema's government said they were being released on humanitarian grounds and for health reasons.

Zuma's spokesman Vincent Magwenya had initially denied Zuma, who is on his second visit to the country in around a year, had intervened with Nguema on the mercenaries' behalf.

On Tuesday, Magwenya told the German Press Agency dpa: "The answer is categorically 'No'... The president did not intervene."

But after Du Toit's remarks he later confessed to The Star that Zuma "might have discussed the plight of the prisoners when he visited the country last year, before he became president."

Zuma was already leader of the ruling African National Congress (ANC) at the time.

Du Toit's remarks were likely to raise questions about South Africa's in Africa's third-largest oil producer, which has a poor record on human rights.

South Africa takes a dim view of mercenary activity and has passed laws that ban its citizens from acting as guns-for-hire anywhere in the world.

Mann, 57, was only a year into his 34-year sentence in Equatorial Guinea. Before that, he had spent four years in prison in Zimbabwe, where he and 61 others were arrested trying to secure weapons for use in the botched plot.

Du Toit, an arms dealer, who was nabbed as he waited in Equatorial Guinea for Mann's group to arrive, and also sentenced to 34 years, had served five.

Mark Thatcher, the son of former British prime minister Margaret Thatcher was implicated in the coup. He received a suspended sentence and a fine at a trial in South Africa in 2005. (dpa)