Mr Denard refers to himself by the military title 'Colonel'

Mr Denard, aged 70, who refers to himself as "Colonel" and Dominique Malacrino deny the charges. A third accused, Jean-Paul "Captain Siam" Guerrier, failed to surrender for the trial and may be tried in absentia.

The trial comes just days after the Comoros experienced its 18th coup in 24 years of independence.

Mr Denard, who began his mercenary career in the Congo, is alleged to have been involved in at least four coups in the Comoros.

The assassinated president, Ahmed Abdallah, was overthrown in the first, shortly after independence. Mr Denard was then instrumental in restoring him to power in the second coup in 1978.

Presidential guard

For 10 years he headed President Abdallah's 500-strong presidential guard and had enormous influence and flourishing business interests in the Archipelago. He eventually became a citizen of the country.

President Abdallah was killed during the third coup in 1989, because - the prosecution alleges - he was about to remove Denard as head of the presidential guard.

The prosecution says Mr Denard hatched a plan to maintain his influence by pretending the army was preparing a coup d'etat against the president, and persuaded him to sign a decree ordering the military to lay down its weapons.

Shortly after signing the order, President Abdullah was shot during a faked attack on his palace on the night of 26 November, 1989.

Mercenary invasion

Mr Denard maintains the president was killed in error by shots fired by one of his own bodyguards. The bodyguard was then killed by the missing defendant.

Mr Denard fled to South Africa shortly after the president's death, but six years later he led a mercenary invasion force to overthrow the then President, Mohamed Said Djohar.

He was then arrested by a French expeditionary force, and spent 10 months in a Paris jail.

Mr Denard has led uprisings in the Belgian Congo, Nigeria, Angola, Zimbabwe - which at the time was white-ruled Rhodesia - Iran and Yemen. He has hinted he had friends and patrons in high places in France.

If found guilty of murdering President Abdallah, he and his lieutenant could face life imprisonment.

But his lawyers say the prosecution case against him is weak and they have little evidence to back up their allegations.