In recent days nearly 2,000 boat people from Myanmar and Bangladesh have been rescued or swum to shore in Malaysia and Indonesia.

The wave of arrivals is believed to be caused by smugglers dumping their human cargo as Thailand moves to stem the trade after discovering dozens of migrant remains in secret jungle camps earlier this month.

The UN refugee agency believes an estimated 25,000 Rohingya and Bangladeshis have taken to boats in the first three months of this year -- double the number over the same period in 2014.

The following is a regional summary of the current "boat people" crisis:

- Malaysia -

Malaysian police say people-smugglers have dumped at least 1,018 migrants in shallow waters off the coast of the resort island of Langkawi since Sunday.

"We know that there are more boats out there that want to come in," Langkawi police chief Haritth Kam Abdullah told AFP on Monday, citing police intelligence.

Some migrants swam to shore after harrowing month-long journeys at sea, packed in with hundreds of other people without adequate food or water.

- Indonesia -
On Sunday Indonesian authorities intercepted a boat off the coast of northwestern Aceh province rescuing more than 600 migrants, many of whom were desperately weak.

A second vessel carrying about 400 migrants was spotted the following day by Indonesian navy vessels. The boat was damaged but afloat and its captain had fled.

Unlike the earlier boat, these migrants did not land in Aceh. Indonesia's navy confirmed Tuesday it had provided the boat with fuel and then towed it out of their waters, declining to say if it was heading to Malaysia, its suspected destination.

- Thailand -

Thailand's national police spokesman Prawut Thavornsiri told AFP Tuesday that aviation police were using helicopters to scour the Andaman Sea for migrant boats while marine police were patrolling the shore.

He added that no new migrant boats had been detected at the common entry points of Ranong and Satun coastal provinces since the recent police crackdown.

However Chris Lewa from The Arakan Project, a respected Rohingya rights group that monitors boat crossings, told AFP she believes there is "a boat in distress in Thai waters" near Langkawi, citing contacts in the trade.

"We think there are around 450 people on board," she said, adding there may be a further two boats carrying migrants under control of brokers near Langkawi.

Since May 1 some 250 migrants from Bangladesh and Myanmar have been found in the southern Thai province of Songkhla, bordering Malaysia, seemingly abandoned by traffickers who are on the run from police.

- Bay of Bengal -
Coastal towns along Bangladesh's Cox's Bazaar district and Myanmar's Rakhine State are the start point for most migrant journeys.

Small vessels carry migrants out to larger "cargo" boats moored in international waters, which head towards South East Asia when full.  

Arakan Project's Chris Lewa said her contacts had told her that five cargo vessels left in early May headed east.

"These boats usually carry between 250-800 people. So there could be at least another 1,000 on their way," she said.

Two remain moored in the Bay of Bengal but are not thought to be taking on any more people at the moment, she added.