Dozens of Rohingya refugees are feared dead or missing after their boat capsized off Indonesia's westernmost coast this week, the United Nations said Friday, as local rescuers called off the search despite survivor accounts many were swept away.

The mostly Muslim Rohingya are heavily persecuted in Myanmar, and thousands risk their lives each year on long and expensive sea journeys, often on flimsy boats, to try to reach Malaysia or Indonesia.

Authorities staged a dramatic rescue Thursday of 69 Rohingya who had been adrift at sea for weeks before their boat and another trying to help them capsized a day earlier, with many found clinging to the hull of an overturned vessel.

Survivors told local authorities that as many as 151 refugees were onboard the boat.

If those still missing are confirmed to have died, it would represent the biggest loss of life for the Rohingya at sea this year, according to the UN refugee agency (UNHCR).

"The fear is for those out of the 151, that haven't been so far rescued, is that those lives have been lost or they have gone missing," UNHCR spokesman Babar Baloch told AFP.

But local authorities nixed the search earlier on Friday because there was no list of passengers.

"The search ended on Thursday. All Rohingya refugees on top of the boat yesterday have been rescued," Muhammad Fathur Rachman, an official from the search and rescue agency in Aceh, said through a spokesperson.

The people rescued included 40 men, 18 women and 11 children who were found off Aceh Province on Thursday.

Six others, including four women and two men, were rescued by fishermen a day earlier.

But rescuer Rachman said there was "no additional information that we received about missing persons, and there is no manifest of the boat".

"Our analysis is the boat cannot hold 150 people."

A protection associate for the United Nations refugee agency (UNHCR), Faisal Rahman, told AFP that one of the survivors said "the boat took 151 people -- once the boat capsized, approximately around 50 people (were) maybe missing and passed away".

- Local anger -

At least eight of the refugees were hospitalised on Thursday evening. The search and rescue agency said they were admitted for dehydration.

The others were taken to a temporary shelter at an old Red Cross building in a village near West Aceh district capital Meulaboh.

Survivors said they had travelled from Bangladesh where many have fled into squalid camps to escape persecution at home. Some said they were trying to reach Malaysia via Indonesia.

Many Rohingya make the perilous 4,000-kilometre journey (2,500 miles) from Bangladesh to Malaysia, fuelling a multi-million dollar human-smuggling operation that often involves stopovers in Indonesia.

At the temporary shelter, many of the refugees were eating food cooked by locals, who also gave them used clothes, according to an AFP journalist.

Some were sleeping on a tarpaulin sheet on the floor, using sarongs as blankets.

At dawn, refugees were taking part in morning prayer using donated Korans.

But some locals protested their arrival, unfurling a banner that said they rejected the Rohingya being there.

Some Rohingya boats landing in Aceh in recent months have been pushed back out to sea as sentiment towards the minority group shifts in the ultra-conservative Indonesian province.

Many Acehnese, who themselves have memories of decades of bloody conflict, are sympathetic to the plight of their fellow Muslims.

But others say their patience has been tested, claiming the Rohingya consume scarce resources.

From mid-November to late January, 1,752 refugees, mostly women and children, landed in the Indonesian provinces of Aceh and North Sumatra, according to the UNHCR.

Hundreds remain in limbo at temporary shelters. Some seek to stay in Indonesia and have been caught trying to escape their shelters, while others have paid smugglers to reach Muslim-majority Malaysia.

The UN agency said it was the biggest influx into the Muslim-majority country since 2015.