Thousands of Bangladeshis and Rohingya Muslims fleeing persecution in Myanmar are believed to be trapped at sea in crowded wooden boats in the Malacca Strait and nearby waters and remain "in great distress" as they try and make their way to Malaysia, according to the International Organization for Migration.
"We don’t have an exact number ... but we have seen reports of migrants in great distress coming ashore in Indonesia, and we’ve got reports there are migrants at sea," said Leonard Doyle, a spokesman for the organization.
Chris Lewa, the director of the nonprofit Arakan Project, which has monitored the movements of Rohingya for more than a decade, said she believes that up to 7,000 Rohingya and Bangladeshis are still on small and large boats in waters between Indonesia and Malaysia.
She told The Associated Press that, given the tight confines of the boats and limited access to food and clean water, the health of those stranded is deteriorating, adding that dozens of deaths have already been reported.
"I'm very concerned about smugglers abandoning boatloads at sea," said Lewa.
About 1,600 Rohingya and Bangladeshi refugees have landed in Malaysia and Indonesia over the last two days, apparently after human traffickers abandoned their boats and left the refugees to fend for themselves, officials said Monday.
The developments come as Thailand, usually the first destination in the region's people-smuggling network, announced a crackdown on the trafficking after the discovery of shallow graves in the mountains of the southern part of the country. Thai authorities said the trafficking camps in that region are often used to smuggle Rohingya refugees, a Muslim minority that has been attacked by Buddhist mobs in Myanmar for years, according to Lewa.
Thai authorities have arrested dozens of people in connection with people smuggling, including a powerful mayor, Soe Naing, otherwise known as Anwar, who was accused of being one of the trafficking kingpins in southern Thailand. More than 50 police officers are also under investigation.
Spooked by the arrests, smugglers are abandoning ships, sometimes disappearing in speedboats after giving only rudimentary instructions to passengers on where to head.
"They've been exploited by traffickers, they've been cheated, they’ve been abused, they’ve been tortured in some cases, and they’ve been left to starve. That’s the reason they’re hurting. It’s really quite straightforward," Doyle said.
An estimated 25,000 Bangladeshis and Rohingya Muslims from Myanmar boarded rickety smugglers' boats in the first three months of this year, twice as many as in the same period in 2014, according to the U.N. refugee agency.
One group of about 600 people arrived in the Indonesian coastal province of Aceh on four boats on Sunday. At about the same time, 1,018 landed in three boats on the Malaysian resort island of Langkawi.
In a statement, Malaysia's marine police said all those who arrived illegally were arrested and sent to detention centers.
Langkawi’s deputy police chief, Jamil Ahmed, said a Bangladeshi man told police the migrants had not eaten for three days. Ahmed added that most of the refugees were weak and thin and that "we believe there may be more boats coming."
Malaysia, a Muslim-majority country with one of Southeast Asia's wealthier economies, is seen as the preferred destination for Rohingya and Bangladeshi Muslim refugees, because, as Doyle puts it, "Malaysia is a country of co-religionists and will be seen undoubtedly as a place of refuge for them."
"There's hope for them in Malaysia, and that’s where they’re desperately trying to get to — to get away from the problems that they’re suffering from whatever issues that are driving them out in such numbers. Because there’s obviously a sense of desperation here," Doyle said.
Al Jazeera and wire services. Philip J. Victor contributed to this report.