The president of the Libreville Special Military Court, however, rejected requests by lawyers of the nine co-defendants to have Colonel Frederic Bongo appear.

At the time of the failed coup by renegade soldiers on January 7, 2019, the officer was the head of the country's most powerful intelligence service.

He was removed from the inner circle of power nine months later and appointed military attaché for the Gabonese embassy in South Africa.

Bongo, who has ruled the oil-rich equatorial country for over a decade, had a stroke in October 2018 while in Saudi Arabia, where he was hospitalised in Riyadh.

While he was convalescing, his supporters put down the brief coup bid that challenged an elected family presidency that has ruled for more than 50 years.

Bongo took over from his father Omar Bongo Ondimba, head of state from 1967 until he died in 2009.

The nine defendants, on trial since June 18 for "undermining internal security of the State" face life imprisonment if found guilty.

According to their lawyers, they wanted to prevent Frederic Bongo from taking power by force and had been in particular concerned about the presence of "mercenaries" in the country.