Sierra Leone on Wednesday charged former president Ernest Bai Koroma with treason and other offences for his alleged role in what authorities have called an attempted coup on November 26, authorities said.

Koroma, who led the West African nation from 2007 to 2018, had previously been questioned, with authorities saying he was an official suspect in the organisation of the coup attempt.

"The former president is charged with four offences, including treason, misprision of treason, and two counts of harbouring," a statement signed by Information Minister Chernor Bah said.

Sierra Leone on Tuesday charged 12 people with treason in connection with the coup attempt, including Amadu Koita, a former soldier and bodyguard of Koroma.

Koita was widely followed on social networks where he criticised the government of current President Julius Maada Bio.

On November 26, armed attackers stormed a military armoury, two barracks, two prisons and two police stations, clashing with security forces.

Twenty-one people were killed and hundreds of prisoners escaped before authorities were able to regain control after what they deemed a coup attempt by members of the armed forces.

The violence sparked fears of another coup in West Africa, where Mali, Burkina Faso, Niger and Guinea have all experienced putsches since 2020.