More than 1000 people fleeing persecution in Myanmar (Burma) and poverty in Bangladesh have come ashore around Southeast Asia, describing killings, extortion and near-starvation after surviving a harrowing journey at sea.

An increasingly alarmed United Nations warned against "floating coffins" and urged regional leaders to put human lives first.

The US urged governments not to push back new boat arrivals.

The waves of weak, hungry and dehydrated migrants who arrived on Friday were the latest to slip into countries that have made it clear they're not welcome.

But thousands more are still believed stranded at sea in what has become a humanitarian crisis no one in the region is rushing to solve.

Most of the migrants were crammed onto three boats that Indonesian fishermen towed ashore, while a group of 106 people were found on a Thai island known for its world-class scuba diving and brought to the mainland.

"If I had known that the boat journey would be so horrendous, I would rather have just died in Myanmar," said Manu Abudul Salam, 19, a Rohingya from Myanmar's Rakhine state where three years of attacks against the long-persecuted Muslim minority have sparked the region's largest exodus of boat people since the Vietnam War.

Manu was aboard the largest boat to come ashore on Friday, a wooden vessel crammed with nearly 800 people that was towed to the Indonesian village of Langsa in eastern Aceh province.

The vessel was at sea when authorities around the region began cracking down on human trafficking two weeks ago.

Aid groups and rights workers have warned that the crackdown prompted some captains and smugglers to abandon their ships and leave migrants to fend for themselves - a claim that was corroborated by survivors who came ashore.

A 19-year-old Bangladeshi survivor, Saidul Islam, said that dozens died on the ship from starvation and injuries after fighting broke out following the captain's evacuation.

His voyage lasted three months, starting when a man turned up at his village and asked if anyone wanted a boat ride to Malaysia, known for better job prospects.

But once at sea, the captain demanded hundreds of dollars and made the men call their families to secure payment. There were also beatings aboard the vessel, which was stifling hot and cramped.

"We could not stand up. When we asked for water, the captain hit us with wire," he said.

Southeast Asia for years tried to quietly ignore the plight of Myanmar's 1.3 million Rohingya but is now being confronted with a dilemma that in many ways it helped create.

In the last three years, more than 120,000 Rohingya have boarded ships to flee to other countries, according to the UN refugee agency.