Fresh clashes raged in New Delhi in protests over a contentious citizenship law on Monday, hours ahead of a visit to the Indian capital by US President Donald Trump.

India has seen weeks of demonstrations and violence since a new citizenship law -- that critics say discriminates against Muslims -- came into force in December.

The latest unrest erupted between several hundred supporters and opponents of the law in a Muslim-dominated area of northeast Delhi on Sunday, and continued into Monday with police seeking to restore order.

The Press Trust of India said protesters torched at least two houses and a fire engine, with local TV channels showing plumes of black smoke billowing from buildings. And two Indian newspapers reported online that a police officer had died.

Riot police fired tear gas and conducted baton charges, local media said. Arvind Kejriwal, Delhi's chief minister, tweeted: "Very distressing news regarding disturbance of peace and harmony in parts of Delhi coming in."

He urged the home minister to "restore law and order" and ensure "peace and harmony is maintained." Trump arrived in the western state of Gujarat on Monday and addressed a huge rally with Prime Minister Narendra Modi before he visited the Taj Mahal monument.

The US president was due in Delhi on Monday evening before official talks in the city on Tuesday. The new law has raised worries abroad -- including in Washington -- that Modi wants to remould secular India into a Hindu nation while marginalising the country's 200 million Muslims.

A senior US official told reporters Trump would raise concerns about religious freedom in the Hindu-majority nation during the trip, calling them "extremely important to this administration".