A judgement sent to French media outlet AFP from the Central African Republic's justice ministry said former President Francois Bozize was sentenced on Thursday.
The 76-year-old Bozize seized power in 2003 but was toppled a decade later. He was in exile in Chad until March when he moved to Guinea Bissau.
He leads the Coalition of Patriots for Change, an alliance of rebel groups that was formed in December 2020. The government alleges the group aims to overthrow Bozize's successor, Faustin Archange Touadera.
Two of Bozize's sons and 20 others, including rebel leaders, were handed the same sentence as the ex-president, also in absentia.
The judgement handed by an appeals court in the capital Bangui said the accused also were convicted of compromising the internal security of the state and "murders," but gave no details on the period concerned or the crimes.
Civil conflict has torn CAR, one of world's poorest countries, since 2013 when Muslim-dominated armed groups ousted Bozize. He later set up armed militias known as the anti-Balakas, who were mainly Christian, to try to regain power.
The conflict lost intensity from 2018, but the country still suffers bouts of violence and remains deeply poor.