Thailand and Malaysia may set up camps to shelter hundreds of refugees arriving on their shores, officials say, after reports that at least 8,000 people are still adrift at sea.

The International Organisation for Migration (IOM) said these refugees are from Myanmar and Bangladesh and called on south-east Asian governments to rescue thousands of them.

"Up to 8,000 people are at sea, of which more than 1,000 have landed," IOM spokesman Joe Lowry said.

"We believe there are no more departures from the Bay of Bengal because of a crackdown by Thai authorities but those who are still at sea have been there for weeks or even months."

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Thailand's Bangkok Post reported national police chief Somyot Pumpunmuang had proposed setting up official camps, although he conceded the plan might only attract more refugees.

Malaysian officials are struggling to deal with the sudden surge of refugees.

"We have room at the detention centre now, but if it is insufficient the ministry has the power to declare a new detention centre," deputy interior minister Wan Junaidi Tuanku Jaafar said.

"This is the first time there is such a big influx of people coming into the country.

"We were told that it was the result of borders set up by the Thai authorities, so we need to find that out as well, whether Malaysia was their final destination."

There has been a sharp increase in refugees arriving from impoverished Bangladesh and Myanmar to Malaysia and Indonesia following a crackdown on trafficking by Thailand.

Bangkok is usually the first destination in the region's people-smuggling network.

Human rights groups concerned for asylum seekers

Mr Lowry from IOM said tackling the problem of migrants arriving by sea is "a regional effort".

"We don't have the capacity to search for them, but governments do, they have boats and satellites ... the journeys are long and a long time at sea isn't good for humans ... they need to be found," he said.

He said the refugees may be in a "very bad condition or even dead" if not found soon.

The United Nations refugee agency echoed the deepening concerns over the condition of those still on the boats

"From survivors we hear there is very little food and water to begin with," UNHCR spokesperson Vivian Tan said.

"If they have been there for weeks or months there is a concern that people come in severely sick."

On Tuesday, Indonesia turned back one boat believed to be carrying around 400 mainly Rohingya Muslims, after giving them fuel, food and water.

Three other boats washed up near the Malaysian holiday island of Langkawi at the weekend.

It is believed the boats had been destined for Thailand, but have been unable to dock because of a crackdown on people smuggling by the Thai military.

ABC/wires