Authorities in northern India say a suspected short circuit sparked a fire on a passenger bus and rapidly engulfed the vehicle in flames, burning at least 20 people to death.

In the aftermath of a deadly militant attack in Kashmir in April, authorities have expelled more than 1,500 Muslims from India, often at gunpoint.

The mismatch poses a dilemma in case of war: either endure Chinese missile strikes deep inside India without the ability to retaliate, or go nuclear.

At least 20 people were killed in a bus fire on a highway in western India, police say, adding that a jammed door kept many passengers from escaping.

The man has been charged with threatening behaviour and causing a public disturbance. Police indicated that his erratic actions may have been triggered by hallucinations linked to cannabis use.

Police officers responding to the scene found the man, identified as Sahil Ram Thadani, 41, behaving erratically and waving the lighter at pedestrians.