The hearing, which is due to begin during the morning, is taking place in a military court inside the Ndolo military prison in the capital Kinshasa.

Armed men attacked the home of Economy Minister Vital Kamerhe in the early hours of May 19 before moving onto the nearby Palais de la Nation that houses President Felix Tshisekedi's offices.

The army later announced on national TV that security forces had stopped "an attempted coup d'etat".

The plot was led by Christian Malanga, a Congolese man who was a "naturalised American" and who was killed by security forces, army spokesman General Sylvain Ekenge said.

Ekenge said the attackers were made up of "several nationalities" and that around 40 were arrested, with another four -- including Malanga -- killed.

Malanga's son, Marcel Malanga, was also among the assailants.

The motive behind the coup bid remains unclear, but the government condemned it as an "attempted destabilisation of the institutions".

A court document shows that 53 defendants will be tried, including Christian Malanga, even though he is dead.

His son, who is American, as well as two other US citizens will also be tried.

At least one Congolese man who is a naturalised Belgian is also among the defendants.

The charges in the case are "attack, terrorism, illegal possession of weapons and munitions of war, attempted assassination, criminal association, murder (and) financing of terrorism", according to the document.

A separate investigation is being carried out into extrajudicial executions allegedly committed by soldiers after the operation.