A cannibal king cobra was caught devouring a smaller snake on a roadside in Thailand.

Drivers were alarmed when they saw the huge reptile blocking a lane on the road while swallowing a smaller cobra in Nakhon Si Thammarat province on February 15.

Lieutenant Pornpitak Chimkhonburi and Sergeant Major First Class Pantharet Sampaosong of the Sichon Special Combat Training Camp received a report at 5:34 pm.

They went to the scene and found the 15ft-long king cobra devouring a smaller cobra while hidden in the tall grass.

The creature regurgitated its meal and was hauled back to the military camp.

The snake was found just an hour after another cobra had been spotted along the same area. Authorities said both cobras will be released into the forest, away from the road.

King cobras have been found to commonly engage in snake-eating or 'ophiophagy'. The behaviour is believed to stem from competition over mates and limited resources.

They are also one of the most dangerous snakes in the world for humans. Researchers found that 7,000 people are treated for snake bites each year in Thailand. Suchai Suteparuk from the Division of Toxicology at Chulalongkorn University reported that 30 of those die, with cobras being the biggest killer.