Diane, who was a key member of Conde's team from 2015 to 2021, has been detained since 2022 and a special court in December sentenced him to prison for embezzlement, illicit enrichment, money laundering and the corruption of public officials.

He has pleaded innocent before the appeals chamber of the Court for the Repression of Economic and Financial Offences (CRIEF), an anti-corruption court which the military rulers set up after ending Conde's 11-year reign in 2021.

"I reaffirm my innocence in the face of the charges I face which are not based on any tangible evidence and do not have a solid legal basis," said Diane, who slammed what he termed "flagrant irregularities" in the case.

"It is evident that my conviction is based on vague, unsubstantiated allegations, which constitutes a flagrant violation of the fundamental principles of criminal law," added Diane, who is being held at the central prison in Conakry and who has never agreed to submit to CRIEF questioning.

He is the latest of many former leaders, opposition figures and civil society members to be detained or brought before the courts under the junta.

Last saw former prime minister Ibrahima Kassory Fofana sentenced to five years for embezzlement. He had faced charges similar to Diane.

Fofana had headed the government under president Conde from May 2018 until the military seized power in a September 2021 coup.

Fofana was notably accused of embezzling 15 billion Guinean francs ($1.7 million) earmarked for anti-Covid measures and economic and social programmes.

Guinea's military leaders have promised to prioritise combatting endemic corruption in the impoverished west African state.

In November 2022, the junta ordered prosecutors to take legal action against more than 180 officials and ex-ministers.