Members of a right-wing paramilitary unit in Colombia say they have killed twenty-three people who they seized three weeks ago.

A statement from the group, which has been blamed for dozens of other mass killings, said the captives were guilty of belonging to guerrilla groups.

The people were kidnapped during an attack on a town in the north of the country, in which several people were murdered.

Troops have been sent to the town to prevent violence during a protest strike planned for later today A government committee led by the interior minister and the prosecutor-generalis also going to the region to investigate the murders.

Human rights groups say the authorities have failed to tackle paramiltiary violence, which often involves members of the army and police.