The death toll from violent protests in northeast India against an Anti-Muslim citizenship law has risen to six, as authorities maintain internet bans and curfews to quell the unrest.

Tension remains high at the epicenter of the unrest in Assam state's biggest city, Guwahati where troops are patrolling the streets in vehicles amid tight security.

Some five thousand people took part in a fresh demonstration in Guwahati on Sunday, with hundreds of police watching on.

In West Bengal, internet services remained suspended in several districts where protests stretched into a third day. The demonstrators set fire to tyres, staged sit-ins on highways and railway tracks, and torched trains and buses.

The legislation, passed by the Indian parliament on Wednesday, allows grant of citizenship to millions of illegal immigrants except Muslims, who entered India from the neighbouring countries on or before December 31, 2014.

The new law is considered by Islamic groups, the opposition, rights activists and others, as part of Prime Minister Narendra Modi's Hindu-nationalist agenda to marginalize the country's 200 million Muslims.

NNR/Zunera