At least 12 Rohingya Muslims - including 10 children - died when their boat capsized as they attempted to flee to Bangladesh from Myanmar, it was reported on Monday.
Officials say the bodies of 10 children, a woman and a man have been recovered so far.
"Observers believe as many as 100000 more people may be waiting to cross into Cox's Bazar from North Rakhine's Buthidaung township (in Myanmar)", the IOM said.
More than a half-million Rohingya have fled Myanmar since August due to reports of suspected ethnic cleansing.
Almost 520,000 Rohingya Muslims have fled Rakhine state for Bangladesh since late August after the military in Myanmar launched a crackdown following attacks by Rohingya militants. He equivocated on whether it amounted to ethnic cleansing, preferring instead to describe the situation as a "human tragedy", global media reports quoted Patrick Murphy, a senior US official for Southeast Asia, as saying before the House Committee on Foreign Affairs.
Most Rohingya are stateless and many fear they will not be able to prove their right to return.
The United States and Britain have warned Myanmar the crisis is threatening to discredit significant progress made by the country since it began moving away from military rule.
Officials worked through the night and discovered 12 bodies.
Sunday's apparent accident was the latest involving refugees. On Sept. 28, a boat carrying about 80 refugees overturned, there were only 17 survivors.
In early September, 46 bodies were recovered after a boat sank in the narrow stretch of water that separates Myanmar and Bangladesh.
The refugees are fleeing a military operation in Myanmar amid which security forces and Buddhist mobs have killed men, women and children, looted homes and torched Rohingya villages.