The U.N. refugee agency on Friday estimated at least 427 Rohingya refugees fleeing Myanmar and Bangladesh died at sea in May.
UNHCR said it has collected reports from family members and others of two separate boat tragedies off the coast of Myanmar in May. It acknowledged that details remained unclear but that enough information has been collected and verified to bring the incidents to light publicly.
About 1 million Rohingya, who are predominantly Muslim, are in camps in Bangladesh after leaving Myanmar. They include about 740,000 who fled a brutal "clearance campaign" in 2017 by Myanmar's security forces, who were accused of committing mass rapes and killings.
A first boat that left from a refugee camp in Cox's Bazar, Bangladesh, and traveled to Rakhine State in neighboring Myanmar to pick up more people sank on May 9, with only 66 survivors among a total of 267 people on board, UNHCR said.
The Geneva-based agency said reports indicated a second boat with 247 people on board that made a similar journey capsized a day later, with only 21 survivors.
"Reports have been coming in and it has been very hard to confirm what has happened, but the fear is that this number of people may have lost their lives at sea in the region," said UNHCR spokesman Babar Baloch.
"Before these two tragedies, some 30 Rohingya were reported to have died or gone missing in boat journeys in 2025," he said. "So if confirmed, this is a huge jump."
Thousands of Rohingya each year attempt to cross the Bay of Bengal and the Andaman Sea, and often the fates of those who have gone missing go unexplained. Even when officials knew the boats' locations, maritime authorities to rescue some of them have gone ignored, UNHCR has said.
A total of 657 people died or went missing in the regional waters in more than 150 boat journeys by fleeing Rohingya last year, UNHCR said.
The recent monsoon season brought perilous maritime conditions including strong winds, rain and rough seas, UNHCR said, adding that it was investigating reports about the fate of a third boat carrying 188 Rohingya that left Myanmar on May 14.
Many Rohingya have fled by sea to Indonesia, which has reported an increase in the number of Rohingya refugees in recent months.
