Leonidas Vargas, who was convicted of drug trafficking, was murdered in a hospital bed where he was being treated for lung disease, a police spokesman said.

Police and hospital chiefs said at least one person entered the 60-year-old's room at Doce de Octubre Hospital and fired four shots.

Vargas was arrested in Madrid in July 2006 and convicted of possessing 500kg of cocaine.

When he was arrested near a Madrid hotel he also had a fake Venezuelan passport and the Colombian Embassy said he had worked with such drug lords as the late Gonzalo Rodriguez Gacha and Pablo Escobar, the Medellin cartel leader who was killed in shootout with Colombian police in 1993.

After Escobar's death, his cartel's role as a major drug smuggling ring was taken by the Cali cartel which the Rodriguez family controlled.

Vargas had been sentenced to 19 years in prison and was transferred to the Madrid hospital for medical treatment on January 2.