A French businessmen described his 17 years in solitary confinement in a seven-square-metre cell in an interview with RFI on Wednesday. Despite his ordeal Cameroon-born French citizen Michel Thierry Atangana urged French companies to continue to invest in the country.

Atangana was jailed for 15 years following a controversial embezzlement conviction and then sentenced to a further term.

He was pardoned in late February by a decree signed by long-serving Cameroonian president Paul Biya.

"I was not sure I would be released," said Atangana, " I wrote to Paul Biya, appealing for my release, and I thank him. I do not blame him for my imprisonment. It was people close to him, who acted in bad faith, who orchestrated a judicial farce with the sole ambition of clinging to power, no matter how undignified the means."

But Atangana declared that Cameroon is a risk worth taking for French companies.

"France can help Cameroon to grow, by bringing technologies and creating jobs," he said. "President Paul Biya is doing everything he can to make this happen."

Atangana arrived last Friday in France, where he saw his family for the first time since 1997.

He told RFI that communications with French authorities were long absent until they were established under president Nicolas Sarkozy.

Atangana said they remained consistent under current president François Hollande.