The UN refugee agency said it was "greatly concerned" for the safety and security of the seven men who were returned to Myanmar from India on Thursday.

The men, who had been in detention for immigration offences since 2012, were handed over to Myanmar authorities at a border crossing in India's northeast state of Manipur.

Before their deportation, the UN had voiced concern that returning the men ignored the danger they faced in Myanmar, where for decades the Rohingya have been targeted in violent pogroms by security forces.

UNHCR voiced concern that the Indian authorities had not  responded to its request that they assess the men's claims to international refugee protection in the country.

"UNHCR regrets that the agency did not receive a response to this request and was unable to secure access for a lawyer from a state legal service," agency spokesman Andrej Mahecic told reporters in Geneva.

- Refoulement laws -

"UNHCR continues to seek clarifications from the authorities on the circumstances under which these individuals were returned to Myanmar," he said.

He said the UN agency was "concerned that they did not have access to legal counsel, were not given the chance to access asylum processing and have their claims assessed in India."

The UN special rapporteur on racism, Tendayi Achiume, warned India on Tuesday that it risked breaking international laws on refoulement -- the return of refugees or asylum seekers to a country where they could be harmed.

The Rohingya are despised by many in Buddhist-majority Myanmar, which refuses to recognise them as citizens and falsely labels them "Bengali" illegal immigrants.

They were concentrated in Rakhine state, the epicentre of a Myanmar army offensive that over the past year has driven some 720,000 Rohingya Muslims into Bangladesh.

Myanmar's army has denied nearly all wrongdoing, insisting its campaign was justified to root out Rohingya insurgents.

But a UN fact-finding mission said there was enough evidence to merit prosecution of several top Myanmar military commanders for crimes against humanity and genocide against Rohingya civilians.

New Delhi considers the Rohingya a security threat, pointing to intelligence which it says links the minority group to extremist organisations.

The government had ordered last year that all Rohingya inside India -- New Delhi puts the figure at 40,000 -- be deported.

The Supreme Court is considering a petition challenging the order as unconstitutional.

The UNHCR said Friday there are 18,000 Rohingya refugees and asylum seekers registered with the agency in India.