A video has emerged in various Islamic State (IS) affiliated chat groups of a teenage Malaysian militant earnestly declaring his support for the terror outfit.

Wearing black and a balaclava, the militant, believed to be a 17-year-old boy from Kuala Lumpur is also seen holding the IS flag and a bottle stuffed with cloth most likely to be a molotov cocktail.

Inspector-General of Police Tan Sri Mohamad Fuzi Harun said the Bukit Aman Special Branch Counter-Terrorism Division has detained the suspect on April 20.