The 28 were convicted of acts including homicide, forced disappearances and displacements, and gender-based violence, "in patterns of systematic, widespread and repeated criminality," said a statement from the prosecutor's office.

This, it went on, was "part of an established directive aimed at violently gaining territory, regardless of the impact on the civilian population, especially of women, Afro-Colombians and indigenous people."

The sentence was issued by a court in Medellin under the Justice and Peace system created in 2006 as part of the process of demobilizing far-right militias.

Justice and Peace provides for maximum sentences of eight years for former paramilitary fighters who confess to their crimes -- including crimes against humanity -- and for lesser penalties for people who provide information about their crimes.

The ruling requires demobilized fighters to make economic and symbolic reparations and "seek forgiveness" from the 6,069 victims and families.

Those sentenced are further required to "commit themselves not to again carry out such punishable behaviors."

The former combatants were part of the Elmer Cardenas unit of the since disbanded United Self-Defense Forces of Colombia (AUC).

Among those sentenced is the unit's chief, Fredy Rendon Herrera, known as "El Aleman," who was earlier convicted for a role in the 1999 abduction of Senator Piedad Cordoba. She was subsequently freed.

For a half-century Colombia has been riven by combat between leftist guerrillas, rightist paramilitaries, drug traffickers and state security forces.

In 2016, the government of President Juan Manuel Santos signed a peace agreement with the Revolutionary Armed Forces of Colombia (FARC), the country's largest rebel group, which has since transformed into a political party.

Santos is continuing negotiations with the National Liberation Army (ELN), the last remaining rebel group.