"The release of Gloria Polanco, Luis Eladio Perez, Orlando Beltran and Jorge Gechem is very positive news but we must not forget about the hundreds of civilians who are still being held hostage across Colombia. They must be immediately and unconditionally released," said Susan Lee, director of Amnesty International’s Americas Programme.

All parties in Colombia's long-running armed conflict -- the security forces, paramilitaries acting alone or in conjunction with the armed forces, and guerrilla groups -- continue to abuse human rights and violate international humanitarian law.

"We urge both sides in the conflict to stop targeting civilians and call on the Colombian government to investigate all human rights abuses committed in the country and to bring those responsible to justice," said Susan Lee.