A demonstrator attends a protest against riots following clashes between people demonstrating for and against a new citizenship law in New Delhi, India, March 3, 2020. ADNAN ABIDI/REUTERS

Delhi — The United Nations human rights agency is seeking to join a case in India's top court against a controversial new citizenship law that many say is unconstitutional for discriminating against Muslims.

The U.N. High Commissioner for Human Rights has filed an unprecedented plea with India's Supreme Court, asking to be made a party in the case against the Citizenship Amendment Act, or CAA.

"The High Commissioner seeks to intervene as amicus curie (a third party) in this case, by virtue of her mandate to inter alia protect and promote all human rights and to conduct necessary advocacy," according to the petition filed with the court by the office of U.N. High Commissioner for Human Rights Michelle Bachelet.

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The new law, which has driven weeks of protests and sparked deadly religious clashes, makes it easier for persecuted minorities from three neighboring countries — Pakistan, Afghanistan, and Bangladesh — to gain Indian citizenship, but it specifically excludes Muslims.

The widespread protests against the new law, and against the government's plan to roll out a National Register of Citizens (NRC) scheme that is also deemed by critics to be inherently anti-Muslim, have claimed 67 lives nationwide.

Of those deaths, 46 people were killed last week alone in India's capital city of Delhi, when mobs shouting religious slogans ransacked at least 10 neighborhoods, shooting people, burning houses, shops and vehicles.

India lashed out at the UN rights panel's bid to intervene, insisting that the Citizenship Amendment Act was an "internal matter."

"We strongly believe no foreign party has any locus standi on issues pertaining to India's sovereignty… CAA is constitutionally valid and complies with all requirements of our constitutional values," India's External Affairs Ministry said Tuesday.

In its petition, the U.N. rights agency asked the Supreme Court to "take into account international human rights laws, norms, and standards… so important for India and the diverse communities it has welcomed" as it weighed the case against the CAA.

"I am concerned by reports of police inaction in the face of attacks against Muslims by other groups, as well as previous reports of excessive use of force by police against peaceful protesters," Bachelet said in the wake of last week's sectarian clashes in Delhi.

The Hindu nationalist government of Prime Minister Narendra Modi, which pushed hard to get the new law enacted, has repeatedly rejected calls to repeal it.

India's Supreme Court is set to hear almost 150 petitions challenging the legality of the new citizenship law. The court declined to suspend the law in January, instead giving the government four weeks to respond to criticism.

The government hasn't responded yet.