Nearly 800 "boat people" were brought ashore in Indonesia on Friday, but other vessels crammed with migrants were sent back to sea despite a UN call to rescue thousands adrift in Southeast Asian waters with dwindling supplies of food and water.
Underlining the hardening of Southeast Asia government's stance on the boatloads of Rohingya Muslims fleeing persecution in Myanmar, Thailand's prime minister warned on Friday that if more migrants arrived they might steal jobs from Thais.
About 2,500 migrants have landed on Indonesia's western tip and the northwest coast of Malaysia over the past week.
But two boats that crossed the Malacca Strait from the Thailand-Malaysia side have been turned away by the Indonesian navy, and on Friday another was towed out to sea by the Thai navy and was heading toward Indonesia.
Malaysia, too, has said it would push migrant boats back to sea as Malaysian people did not want to see large numbers arriving in the country.
"The situation is very grave," said Joe Lowry, a spokesman for the International Organization for Migration in Bangkok.
"They have no food, no water and are drinking their own urine. This is a game of maritime ping-pong with human life. We expect governments in the region to find a solution rapidly … or we will be finding boatloads of desiccated corpses floating around in the Andaman Sea in coming days."
The crisis has arisen because smugglers have abandoned boats full of migrants, many of them hungry and sick, in the Andaman Sea following a Thai crackdown on human trafficking.
Thailand is the first stop on the most common trafficking route used by criminals preying on Myanmar's Rohingya Muslim minority as well as Bangladeshis seeking to escape poverty.
As some countries faced pressure for closing their doors to desperate "boat people", the UN human rights chief said the deadly pattern of migration by sea across the Bay of Bengal would continue unless Myanmar itself ends discrimination.
"Until the Myanmar government addresses the institutional discrimination against the Rohingya population, including equal access to citizenship, this precarious migration will continue," Zeid Ra'ad Al Hussein said in a statement.
Around dawn on Friday a boat with almost 800 people was brought ashore by fishermen along the coast of Aceh, on Indonesia's western tip, Khairul Nova, a search and rescue official in the nearest town, Langsa, told Reuters by phone.
"What I have been told by some of the people who were on the boat is that the boat was sinking and fighting broke out on board," Nova said. "We have seen many with injuries to the face and head. I don’t know why (the fighting) happened."
However, in the same waters, the Indonesian navy pushed another boat back and Thailand's navy towed a wooden vessel with hundreds, including children, on board back out to sea.
"Those on the boat did not want to come to Thailand so we gave them food, medicine, fuel and water," Thai Lieutenant Commander Veerapong Nakprasit told Reuters.
"We did our humanitarian duty. They did not want to come to Thailand so we sent them on their way. This is not a push-back because these people wanted to go."
Veerapong said the boat was without a captain but that some of those on board had been trained by local Thai fishermen for a few hours to navigate.
The United Nations this week urged governments to fulfill an obligation to rescue those at sea and "keep their borders and ports open … to help the vulnerable people who are in need".
However, there have been few signs that Southeast Asian nations are collaborating to avert a humanitarian crisis, in contrast with Europe, where countries are working together to deal with a tide of migrants crossing the Mediterranean.
Thai Prime Minister Prayuth Chan-ocha, whose government has announced a regional meeting on the crisis for May 29, said his country did not have the resources to look after the migrants.
"As there are many of them, we cannot look after them properly. Where will we put them?" Prayuth told reporters.
"Right now we have to find a place for them to stay. In the future, if many more of them come, it will cause a problem. They will steal the jobs and livelihoods of Thais."
Both Malaysia and Thailand have called on international organizations to help meet the cost of dealing with the crisis.
"We're starting to see politicians squabbling over what's fair and not fair for them when it comes to a response to dealing with these people," said Matt Smith, executive director of the Bangkok-based group Fortify Rights. "It's a callous response when we know people are dying at sea."
The United States last year downgraded Thailand and Malaysia to its list of the world's worst centres of human trafficking, dumping them in the same category as North Korea and Syria.