Marafa, the ex-minister of territorial administration and decentralisation, was sentenced along with three others who also received the same sentence, including the former head of the now defunct airline Camair, Yves Michel Fotso.

"I am disappointed but not beaten," Marafa told the court, declaring himself a victim of "slanderous accusations".

Two women were also sentenced to 10 and 15 years.

They must jointly pay $42 million in damages and interest to the state plus more than $2 million in costs.

Marafa, once one of the most powerful men in Cameroon, was charged with overseeing the presidential jet project in his role as secretary general to the presidency.

Following the downpayment debacle, Cameroon rented another plane called the Albatross but this proved defective during a first flight with the presidential family and was forced to make an emergency landing.

At the beginning of May, a former ambassador to the United States, Jerome Mendouga, was jailed for 10 years in connection with the same affair.

Cameroon President Paul Biya, who has been in power since 1982, has launched a major drive against corruption, which has seen several of his former aides brought before the courts.

He won election to a sixth term of office in October 2011 in a vote widely criticised by the opposition and diplomats as riddled with irregularities and fraud.