Union Home Minister Rajnath Singh on Monday said that states have been asked to identify Rohingya refugees and collect their biometric data, the report of which will be sent to Myanmar.

"States have been told to identify them (Rohingya). They have to take their biometrics also. After that, they will send a report to the Centre. Then the central government will initiate action through diplomatic channels with Myanmar and then we will get it resolved," Rajnath Singh told reporters.

Singh was in Kolkata to chair the 23rd meeting of the Eastern Zonal Council, which was attended by West Bengal Chief Minister Mamata Banerjee, her Jharkhand counterpart Raghubar Das and Bihar Deputy Chief Minister Sushil Modi.

The development has come a day after the Railway Protection Force (RPF) alerted the Kerala authorities to watch out for the movement of Rohingya refugees in groups to Kerala and hand them over to police if they are found travelling on trains.

More than 650,000 Rohingya Muslims fled Rakhine in August 2017 after Myanmar's army launched a massive crackdown in its northern state, retaliating the attacks by insurgents, Arakan Rohingya Salvation Army on the country's police posts and a military base.

A large number of Rohingya refugees, since then, have taken shelter in India and Bangladesh, and are staying in refugee camps, often raising security concerns.

In June, the Home Ministry wrote a letter to the Jammu and Kashmir government, saying, "Such illegal migrations poses serious challenges and has security implications since some of the migrants have been found to have indulged in illegal activities and are vulnerable to radicalisation."