LANGKAWI - Malaysia joined Indonesia on Wednesday in vowing to turn back vessels bearing a wave of migrants, drawing warnings that the hardline policy could be a death sentence for boatloads of people at risk of starvation and disease.
As the UN's refugee agency accused regional authorities of playing with lives, more grim accounts emerged from among hundreds of ethnic Rohingya refugees from Myanmar and impoverished Bangladeshi migrants who have endured weeks of torment at sea.
Mizanur Rahman, a 14-year-old Bangladeshi boy, said he and a friend spent two agonising months crammed aboard a boat with an estimated 600 other people.
They subsisted on a single plate of rice per day, but were given nothing to eat in the final two weeks, Rahman told AFP.
Others aboard that vessel said they saw at least six people die of sickness or hunger, only to have their bodies tossed overboard, and that some passengers were beaten by gun-toting smugglers.
They spoke in the northern Indonesian region of Aceh, where survivors from the ship washed up this week after traffickers told them to "swim to shore if we wanted to stay alive," according to Rahman.
"We wanted to go to Malaysia, dreaming of a better future for our families. After everything that happened to us, I would now prefer to die here rather than go back home," Rahman said.
Migrant-rights advocates are warning that thousands more men, women and children are believed stuck at sea and at risk of abandonment by smugglers since a Thai police crackdown disrupted people-smuggling routes.
Thailand has called for a May 29 regional summit to address what it called an "unprecedented increase" in migrant arrivals.
But Malaysia - where more than 1,100 migrants came ashore this week - said it would turn away boats entering its waters unless they were about to sink.
"The policy has always been to escort them out of Malaysian waters after giving them the necessary provisions" including fuel, water and food, First Admiral Tan Kok Kwee of the Malaysian Maritime Enforcement Agency told AFP.
The Indonesian navy already has turned away at least one vessel packed with hundreds of abandoned migrants.
Vivian Tan, Bangkok-based spokeswoman for the UN High Commissioner for Refugees (UNHCR), said the policy was "really worrying".
"We continue to appeal for countries in the region to share responsibility and avert a humanitarian crisis," she said.
"The first priority should be to save lives and provide humanitarian aid." Joe Lowry, spokesman for the International Organisation for Migration (IOM) in Bangkok, said authorities were playing "maritime ping-pong".
"What we want is for governments to allow people to disembark so they can be treated and policy can be worked out later," he said.
Otherwise, "people are going to die in the hundreds and thousands on the sea".
The UNHCR says about 25,000 people embarked from Bay of Bengal ports in January-March, double last year's rate.
Thousands of them are feared left in the lurch by the crackdown in Thailand, which began after the discovery of dozens of dead migrants in jungle graves along its southern border earlier this month.
Rohingya, a Muslim ethnic group denied citizenship by Buddhist-majority Myanmar, flee by the thousands annually to escape discrimination and sectarian violence that has targeted them in recent years.
The IOM has called for search-and-rescue operations to find stricken migrant boats.
The inter-governmental group has also demanded a coordinated and sympathetic response by Europe as the continent grapples with its own migration crisis originating in North Africa.
A US embassy spokesman in Bangkok called Asia's refugee problem "a regional challenge that needs to be addressed regionally through a coordinated international effort." Thai authorities said they were searching for a one-time senior provincial official in the south who they called the "mastermind" of trafficking along the Thai-Malaysian border, a key link in the chain.
Police said they had seized millions of dollars worth of assets belonging to Pajjuban Aungkachotephan - who is known colloquially at "Ko Tong", or "Big Brother Tong." He is believed to have fled abroad.