Sixteen Colombian police officers killed in helicopter crash while searching for drug lord

Sixteen Colombian police officers have been killed after their helicopter crashed while searching for the nation's most wanted drug lord.

Two other officers were critically injured when the US-made UH-60 Black Hawk came down in a wooded area of north-west Colombia.

The officers were hunting for Dairo Otoniel Usaga, leader of Colombia's most violent drug-smuggling gang.

The area where the helicopter crashed - in dense jungle dominated by drug traffickers and a refuge for leftist rebels - fuelled speculation that the helicopter may have been shot down.

But the country's defence minister said two other helicopters also participating in the mission did not detect any gunfire.

Low-lying cloud likely obstructed the pilot's vision, causing it to crash at 110mph into a hillside, Luis Carlos Villegas added.

The United States is offering a reward of up to $5 million for information leading to the capture of Otoniel, who runs Colombia's most violent drug-smuggling gang.

Since February, efforts to find Otoniel have been stepped up.