THOUSANDS of long-persecuted Rohingya Muslims fleeing Myanmar are believed to be stuck at sea on boats, unable to land because of a crackdown on people-smuggling networks in Thailand and Malaysia, officials and refugee activists say.

Two boats carrying about 500 people washed ashore in western Indonesia's Aceh province on Sunday, including some women and children weak from a lack of food and water and needing medical treatment.

"We received a report from fishermen this morning that there were boat people stranded in the waters off north Aceh," Aceh provincial search and rescue chief Budiawan said.

"We dispatched teams there and evacuated 469 migrants who are Rohingya from Myanmar and Bangladeshis. There are women and children among them. So far, all of them are safe."

He said the group would be taken to a detention centre in the north Aceh district, where police and immigration officials would carry out "further processing", which would include investigating their motives.

Darsa, a disaster management agency official who, like many Indonesians, goes by one name, said the group had arrived near a beach in the north Aceh district early on Sunday.

"One of the migrants who could speak Malay told me that their agent had told them they were in Malaysia and to swim to shore," he said. "Some of them did. But later they found out from fishermen that they were in Indonesia."

According to the migrant, five boats had left Myanmar last week to escape the conflict in their country, Darsa said.

"He said the Muslims were beaten and had hot water poured on them and they just wanted to get out of Myanmar as soon as possible, to anywhere where they could seek refuge," he said.

State-sanctioned discrimination in Myanmar's Arakan state in the past three years has prompted tens of thousands of Rohingya to flee in boats in the highest movement of asylum seekers in the region since the Vietnam War.

In the past their first stop has been in Thailand where smugglers held them captive in jungle camps in brutal conditions while collecting payments before allowing them to continue their journey to Malaysia, Indonesia or other destinations.

But the discovery of mass graves and dozens of captive Rohingya in Thailand's south has prompted a crackdown that has seen the arrest of a powerful provincial mayor, at least six local officials and investigations into 50 police officers.

Chris Lewa, director of the Arakan Project, which has monitored the movements of Rohingya for more than a decade, said as many as 8000 Rohingya and Bangladesh asylum seekers could be parked on boats in the Malacca Straits, unable to come ashore in Malaysia and Thailand.

She said she worries that with limited access to food and clean water their health is steadily deteriorating.

Thousands of Rohingya are known to have been held for weeks or months at a time in ships at sea.

Thai officials and refugee activists say people smugglers spooked by the crackdown are also believed to have taken asylum seekers deeper into the Thai jungle to avoid detection.

A total of 33 bodies believed to be migrants from Myanmar and Bangladesh have been exhumed from graves in various jungle camps in the mountains of southern Thailand in recent days.

Last week Thai police patrolling the Khao Kaew mountain in Padang Besar found 96 people, all frail and hungry, who said they were brought to Thai shores by boat and abandoned by smugglers who promised to take them to Malaysia.

The discoveries have embarrassed Thailand which is already under pressure from the United States and European Union to stop human trafficking on land and in its fishing fleet where conditions on some boats have been described as slave labour.

Prayuth Chan-ocha, the head of Thailand's military-controlled government, has called for a summit hosted by Thailand aimed at tackling human trafficking in Asia with a special emphasis on Rohingya.

Australia's foreign minister Julie Bishop has pledged Canberra's support for the summit.

Mr Prayuth, a former army general, has given Thai security forces 10 days to expose trafficking networks.

"We have to punish the human traffickers strictly, according to the law," he said.

"If any government officials or authorities are involved they will face punishment."

The Bangkok Post said in an editorial that the arrests confirm long held suspicions that government officials have colluded with trafficking networks.

Buddhist-majority Myanmar, which is also called Burma, views many of its population of about 1.2 million Rohingya as illegal Bangladeshi immigrants despite the fact they have lived in the country for generations.

Described by the United Nations as among the world's most persecuted minorities, they have been targeted in outbreaks in sectarian violence in western Myanmar in recent years.

In April a group of regional lawmakers called on the 10-member Association of South-East Asian Nations (ASEAN) to abandon its policy of not interfering in each other's affairs which has been used as justification to avoid holding talks on the plight of Rohingya.

"We are seeing a dire situation in ASEAN," said Charles Santiago, a Malaysian lawmaker and member of the ASEAN Parliamentarians for Human Rights grouping.

He said the flow of refugees fleeing Myanmar is a "human catastrophe".

"ASEAN leaders cannot and should not hide behind the notion of non-interference," he said.

with agencies