Deadly bomb and drone attacks in two different regions of Colombia were being linked to the government's war on narcotrafficking by former FARC rebels.

A Black Hawk was attacked by cocaine-trafficking group, officials said, the latest in an escalating series of drone attacks against security forces.

At least 18 people have been killed and dozens wounded in two separate attacks in Colombia, deepening the country's most serious security crisis in decades. Six people died and more than 60 were injured after a car bomb exploded on a busy street in the western city of Cali in Colombia, according to authorities.