Groups of locals armed with crude implements started attacking students Monday and on Tuesday.

Police and paramilitary troopers were deployed in strength around the campus to prevent further attacks.

'Many students from Assam who boarded buses and other public transport were stopped on the road and forced to get down and then severely assaulted,' the teacher said.

At least 20 students have since been admitted to hospitals with serious injuries.

'There is tension in the area, although things are under control now,' a police official in Gangtok said.

There are some 800 students from Assam studying at the Sikkim Manipal Institute of Technology.