A high court in Sierra Leone has sentenced 11 people including soldiers and police officers to long prison terms for their alleged roles in a failed military coup last year.

Gunmen on Nov. 26 attacked military barracks, a prison and other locations in Sierra Leone, freeing about 2,200 inmates and killing more than 20 people.

After the coup bid collapsed, 12 people were charged in January with treason.

Late on Monday, 11 were convicted in a unanimous jury verdict on 20 counts including treason, murder and unauthorised use of military uniform.

The twelfth accused, Bai Mahmoud Bangura from the opposition All People's Congress (APC) party, is being tried separately due to health issues.

Amadu Koita Makalo, as retired army major and former bodyguard to ex-president Ernest Bai Koroma, received several sentences for various counts ranging from 40 to 70 years in prison, to be served concurrently.

Two female police officers were also sentenced. One of them, Ramatu Kamanda Conteh, was given 30 years for harbouring Koita.

The government said the coup bid was led mostly by bodyguards to Koroma, who was later charged with four related offences, before the government decided to let him leave the country on medical grounds.

Koroma condemned the coup attempt and his lawyers called the charges "trumped up" and part of a "political vendetta".

Tensions have risen anew in Sierra Leone, two decades after a 1991-2002 civil war in which more than 50,000 were killed.