Myanmar authorities on Monday described Bangladesh as "the root" of the migrant crisis facing the region, after hundreds of people -- many from the Muslim Rohingya minority -- were found adrift at sea.

Nearly 2,000 people from Myanmar and Bangladesh had been rescued or swum to shore in Malaysia and Indonesia by late Monday, after people smugglers apparently abandoned them in boats.

As the trafficking trail snaking south from Bangladesh and Myanmar, via Thailand and onto Malaysia, slowly gives up some of its secrets, attention has turned on the departure points for desperate migrants who risk death by taking rickety boats in heavy seas.

More than 1.3 million Rohingya, a stateless Muslim ethnic group viewed by the United Nations as one of the world's most persecuted minorities, live in Myanmar's western Rakhine State.

But authorities deny them citizenship, refusing to recognise them as one of the nation's minority groups and labelling them "Bengalis" -- short hand for foreigners on their soil.

"From a humanitarian perspective, the help given by the Malaysians and Indonesians is very good... but the issue is whether these people -- who say they are from Myanmar -- really come from Myanmar," Zaw Htay, the director of the Myanmar's president office told AFP.

"The root of this problem is Bangladesh. Bangladesh carries the major responsibility for this," he said, disputing the existence of a "Rohingya" minority in Myanmar.

"We do not acccept that term," he added.

Deadly communal violence between local Buddhists and Muslim Rohingya in impoverished Rakhine in 2012 left some 200 dead and tens of thousands -- mainly Rohingya -- trapped in squalid camps, catalysing the latest exodus by sea.

The Rohingya say they can trace their ancestry in Myanmar back generations yet they remain expunged from the nation's official narrative.

Many tens of thousands languish in fetid camps for the displaced, unable to work, attend school or access healthcare.

Their status in Myanmar is an incendiary issue for Buddhist hardliners, moreso ahead of elections this year, which observers fear could be derailed if major communal violence was to re-ignite.

Hundreds of thousands of people, mainly Rohingya, have been told to hand over their temporary identity cards over the last two months after Myanmar's president voided the documents.

"At the moment Rakhine State is stable. But the whole state is still in an emergency situation. People need to understand that," Zaw Htay warned.

Some 300,000 Rohingya also live in coastal Bangladesh bordering Myanmar following decades of discrimination. But only a tiny fraction are recognised as refugees there.

The United Nations refugee agency estimates 25,000 people from Myanmar and Bangladesh have taken to boats headed south in the first three months of this year alone.