Schools in the northeast of the city were shut yesterday and at least five metro stations closed.

An announcement over a mosque loudspeaker urged protesters to stay non-violent and not attempt to cross police barricades.

"We don't have a problem with the police, we are against the government's law," the male announcer said.

India's capital has been a hotbed of unrest against the Citizenship Amendment Act (CAA), which makes it easier for non-Muslims from three neighbouring Muslim-dominated countries to gain Indian citizenship.

The CAA has sparked accusations that Modi and his Hindu nationalist Bharatiya Janata Party are undermining India's secular traditions. The BJP denies any bias against India's more than 180 million minority Muslims but objectors have staging protests and camping out in parts of New Delhi for two months.

Trump praised India as a tolerant country.

"India is a country that proudly embraces freedom, liberty, individual rights, the rule of law and the dignity of every human being," he told a rally of over 100,000 people in Modi's home state of Gujarat. "Your unity is an inspiration to the world."