Rights groups are urging India to abide by its international legal obligations after the government said it was looking to deport tens of thousands of Rohingya migrants.
India's junior home minister Kiren Rijiju told parliament last week the government had asked state authorities to identify and deport the Rohingya, a stateless ethnic minority who mostly live in neighbouring Myanmar, where they face discrimination and violence.
In recent years, thousands have fled across the border to Bangladesh and on to other countries including India, which does not recognise them as refugees even though the United Nations says they are.
Human Rights Watch and Amnesty International said India should abide by its international obligations.
"Indian authorities should abide by India's international legal obligations and not forcibly return any Rohingya to Burma without first fairly evaluating their claims as refugees," said Meenakshi Ganguly, the South Asia director at Human Rights Watch, in a statement on Thursday.
The number of Rohingya migrants has swelled in recent years. Rijiju said in a written response to parliament that around 40,000 were living illegally in India.
Thousands fled Myanmar after a military crackdown last October in Rakhine state launched in response to an armed attack on border posts.
Witnesses brought stories of soldiers raping and murdering Rohingya and of entire villages being burned to the ground in a campaign the UN has said may amount to ethnic cleansing.
"Characterising Rohingya refugees and asylum-seekers as illegal immigrants... takes no account of the reasons why they had to flee their homes and the grave risks they may face if forcibly returned," said Raghu Menon, advocacy manager at Amnesty International India.
"Indian authorities are well aware of the human rights violations Rohingya Muslims have had to face in Myanmar and it would be outrageous to abandon them to their fates."
Despite being home to thousands of refugees, India is not a signatory to the 1951 Refugee Convention or the 1967 Protocol Relating to the Status of Refugees.