JAKARTA (AFP) - Indonesia has begun search and rescue operations for stranded migrant boats carrying Bangladeshis and ethnic Rohingya from Myanmar, an official said on Sunday, after it dropped a hardline policy of refusing them sanctuary.

Jakarta sparked international outrage by turning away vessels filled with desperate migrants, among thousands stranded at sea since a Thai crackdown on human trafficking in early May threw the illicit trade into chaos.

Along with neighbouring Malaysia, the government changed approach on Wednesday with an announcement that they would take in boat people provided they could be resettled or repatriated within a year.

While Indonesian fisherman have helped hundreds of stranded Rohingya and Bangladeshis to shore, so far there has been no official rescue effort from Jakarta.

But four naval ships, two pontoons and a patrol aircraft have now been deployed in a search which started on Friday evening, Indonesian military spokesman Fuad Basya told AFP.

"We have officially received an order from President (Joko Widodo) to carry out search and rescue operations, whether in the Indonesian territory or international waters," he said.

"We will save the migrants and take them to shore," he said, adding that as of Saturday evening, no new boats had been sighted.

The Malaysian government announced on Thursday that its navy and coastguard would be mobilised for search operations but so far it has not reported any rescues either.

More than 3,500 migrants have swum to shore or been rescued off the coasts of Malaysia, Indonesia, Thailand and Bangladesh since the crisis erupted earlier this month.

Boatloads of starving Rohingya and Bangladeshis have been abandoned by smuggling syndicates and left to fend for themselves.