Bogota  - Members of former far-right paramilitary groups in Colombia were responsible for about 25,000 murders in recent decades, a report by the attorney general's office in Bogota said Wednesday.

Around 3,700 militants took part in the violence over a period of 20 years. The perpetrators were offered an amnesty programme between 2003 and 2006 that guaranteed them milder sentences of up to eight years if they confessed to their crimes.

Members of the disbanded United Self-Defence Forces of Colombia (AUC) also admitted responsibility for the disappearance of 2,251 others and the kidnapping of 831 people. In total, authorities were able to find 2,100 graves with the remains of 2,562 people, the report said.

The former AUC members also told justice officials in hearings of numerous acts of collaboration with politicians, police and the military.

Efforts by Colombian President Alvaro Uribe led to the disarmament of some 31,000 paramilitaries between 2003 and 2006. Meanwhile, 247,000 citizens have filed claims as victims of the paramilitaries.  dpa