The Colombian president, Ernesto Samper, says he's confident that the government will soon be able to name those behind the killing of twenty-five people kidnapped in the northern town of Barrancabermeja three weeks ago.

Mr Samper was speaking shortly after a right-wing paramilitary unit which has been blamed for dozens of other mass killings said it was responsible.

The president said Colombian intelligence had compiled plausible evidence on who was behind the murders.

Meanwhile, troops have been sent to Barrancabermeja to prevent violence during a protest strike planned there today, and a government committee led by the interior minister and the prosecutor-general is also going to the town.