UN High Commissioner for Human Rights approached the Supreme Court over the Citizenship Amendment Act

Highlights CAA consistent with "our constitutional values", said MEA

The UNHRC has filed an intervention plea with the top court

Citizenship law has been fiercely opposed by several non-BJP ruled states

In an unprecedented move, and one that signals growing international pressure on India, the United Nations High Commissioner for Human Rights has approached the Supreme Court over "the exclusions of persons... on the basis of their religion" from the controversial Citizenship Amendment Act, or CAA.

The intervention plea - in which the High Commissioner, former Chile President Michelle Bachelet, asks to be made party in a case against the law that is being heard by the top court - has said the "differentiations" drawn by the law are not "sufficiently objective and reasonable".

The External Affairs Ministry hit back in a sharply-worded statement, declaring the CAA an "internal matter and saying "no foreign party had any locus standi on issues pertaining to India's sovereignty".

"The Citizenship Amendment Act is an internal matter and concerns the sovereign right of the Indian parliament to make laws. We strongly believe no foreign party has any locus standi on issues pertaining to India's sovereignty," the ministry said today.

The MEA response also said the CAA, which the government says will help non-Muslim refugees fleeing religious persecution from Muslim-dominated neighbouring countries, is "constitutionally valid" and upholds human rights values.

"It is reflective of our long-standing national commitment in respect of human rights issues arising from the tragedy of the Partition of India," the ministry said.

The government's claim that the CAA will help non-Muslim refugees because Islam is the state religion in the countries listed (Afghanistan, Bangladesh and Pakistan) has been disputed by the petition.

"Recent reports... ascertain there exist a number of religious groups considered religious minorities in these countries, especially of the Muslim faith, including Ahmadi, Hazara and Shia Muslims whose situations would warrant protection on the same basis as that provided in the preferential treatment proposed by the CAA," the petition states.

The Supreme Court is currently hearing a massive 143 petitions challenging the legal validity of the CAA. In a January hearing the court declined to put the law on hold and, instead, gave the central government four weeks to respond.

The CAA, passed by parliament in December, has been fiercely criticised by the opposition and activists as being anti-Muslim and violating secular tenets of the Constitution. It is also feared that the CAA, used with the NRC (national register of citizens) and NPR (national population register) can be used to further target Muslims.

Sustained nationwide protests, some of which have been led by students and women, have broken out since it was passed, with lakhs taking to the streets. A peaceful and weeks-long protest in Delhi's Shaheen Bagh has emerged as the epicentre of these protests.

The protests have drawn the attention of students in foreign countries and celebrities like Pink Floyd co-founder Roger Waters, who this week called the CAA "fascist".

Protests over the law also led to horrific violence in Delhi last week, in which 48 people were killed and hundreds injured.

Shortly after it was passed the United Nations expressed concern over a law that it said was "fundamentally discriminatory in nature". A spokesperson for the Office of the UN High Commissioner for Human Rights (OHCHR) said it would "have a discriminatory effect on people's access to nationality".

Prime Minister Narendra Modi, Home Minister Amit Shah and other BJP leaders have repeatedly defended the bill, which they say will help refugees. They say the opposition is spreading rumours and misinformation about the law for political gain.

Undeterred by the government's claims, the CAA has been opposed by several non-BJP ruled states, such as Bengal, Kerala and Punjab. These states have passed anti-CAA resolutions and, in the case of the first two, have stopped work on NPR and NRC.