A protester reacts from a police van after being arrested at the Town Hall during a demonstration held against India's new citizenship law in spite of a curfew in Bangalore on Thursday. Photo: AFP

Indians defied bans on assembly Thursday in cities nationwide as anger swells against a citizenship law seen as discriminatory against Muslims, following days of protests, clashes and riots that have left six dead.

Two major Indian telecom firms also said Thursday that they have cut mobile services in parts of New Delhi on government orders.

The new law eases citizenship rules for people fleeing persecution from three neighboring countries, but excludes Muslims, stoking accusations that Prime Minister Narendra Modi wants to reshape India as a Hindu nation and creating unease abroad.

Following days of protests that have seen four people shot dead, dozens injured, hundreds arrested and vehicles torched, authorities have banned gatherings in areas that together are home to hundreds of millions of people.

They included Uttar Pradesh state, areas of the northeast and parts of Bihar, New Delhi, Hyderabad, Bangalore and Chennai, all of which have seen protests in recent days, and in the case of the capital violence.

Fourteen Delhi metro stations were shut including one near police headquarters, besieged by protesters earlier this week, as some roads into the megacity were blocked, causing immense traffic jams.

Vodafone and Airtel announced they had cut services on mobiles in some parts of the city and mobile operator Jio is reported to have followed suit.

India is already the world leader in cutting the internet, activists say, and access has been restricted in parts of the northeast and in Uttar Pradesh, home to a large Muslim minority.

Demonstrators on Thursday ignored the bans on assembly including in Delhi and Hyderabad where television pictures showed police dragging and carrying demonstrators away as they brandished placards and chanted slogans.

Protests against the law began in northeast India last week - where all six fatalities took place - but soon spread, fuelled by anger about alleged police brutality including at a university in Delhi on Sunday night.

Security forces in the capital have fired some 450 tear gas shells in the past five days, the Hindustan Times daily ­reported. One student reportedly lost an eye.

Modi has insisted that his government does not aim to marginalize Muslims with the new law. But many in the 200 million strong Muslim minority fear that they will be the main target of Modi's plans to implement a national "register of citizens" to remove all "infiltrators" by 2024.