Thailand's prime minister warned on Friday that if more Rohingya migrants head to the country's shores they might steal jobs from Thais.
Thousands of Bangladeshis and Rohingya Muslims from Myanmar are spirited across the Bay of Bengal by human trafficking networks each year, most thought to be heading to Muslim Malaysia.
But, like Thailand and Indonesia, Malaysia has said it will push boats full of migrants back to sea.
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."
Nearly 800 "boat people" were brought ashore in Indonesia on Friday but other vessels crammed with migrants were sent back to sea despite a U.N. call to rescue thousands set adrift in Southeast Asian waters.
Following a Thai crackdown on human trafficking, smugglers have abandoned ships full of migrants, many of them sick and hungry, in the Andaman Sea.
Thailand is frequently used as a transit route by smuggling networks that prey on migrants from Myanmar and Bangladesh looking to escape ethnic and religious persecution.