Kuala Lumpur/Bangkok: Malaysian Prime Minister Najib Razak said on Thursday he had ordered the navy to conduct search and rescue missions for thousands of migrants adrift at sea as Thailand's prime minister said his country would not provide shelter.

Southeast Asia is battling a migrant crisis that has seen hundreds of ‘boat people’, mostly Rohingya Muslims from Myanmar and Bangladeshi migrants who fled persecution and poverty at home or were abducted by traffickers, pushed back out to sea by Thailand, Malaysia and Indonesia.

Many now face sickness, and possible starvation.

‘I have further ordered @tldm_rasmi (navy) and APMM (Malaysian Maritime Enforcement Agency) to conduct search and rescue efforts on Rohingya boats,’ Najib said on his Twitter account.

‘We have to prevent loss of life,’ he said, adding that humanitarian aid would be delivered by land and sea.

Malaysia and Indonesia on Wednesday said they would let as many as 7,000 migrants on the seas now to come ashore temporarily, but no more.

For decades, ethnic minority Rohingya have suffered from state-sanctioned discrimination in majority-Buddhist Myanmar and are denied citizenship. The Malaysian and Indonesian foreign ministers were in Myanmar on Thursday for talks on the crisis.

Armanatha Nasir, a spokesman for Indonesia's foreign ministry, said Indonesia would not put pressure on Myanmar.

‘We will continue to encourage Myanmar in their process of reform and democratization. Because in the end we believe it will create an environment conducive for the Rohingya.’

The United Nations has been calling on governments in the region to rescue the migrants. More than 3,000 have been rescued by locals or come ashore in Indonesia and Malaysia this month.

Indonesia and Malaysia have said that temporary shelters would be set up to house the migrants but Thailand, a traditional transit point for migrants trying to reach Malaysia illegally to find work, said it would not follow suit.

‘There will definitely be no migrant shelters,’ Thai Prime Minister and coup leader Prayuth Chan-ocha told parliament in Bangkok on Wednesday, adding that existing detention centres would be used to hold those found to have entered Thailand illegally.

Thailand has said it would stop towing boats back to sea, something Malaysia and Indonesia had been doing in recent days, and will allow the sick to come to shore for attention, but has stopped short of saying whether it would allow other migrants to disembark.

Thailand has called a regional conference on the issue in Bangkok for 29 May.