Myanmar started moving people into emergency shelters as a cyclone threatened to batter a violence-wracked region home to tens of thousands of internal refugees.
About 140,000 internally displaced persons (IDPs) living in flimsy tents or makeshift housing are seen as particularly vulnerable to Cyclone Mahasen, which was gathering strength in the Bay of Bengal.
The cyclone is expected to make landfall near the Myanmese-Bangladeshi border on Thursday morning, according to Myanmar's Department of Meteorology and Hydrology.
It said Mahasen, packing winds of up to 100km/h, was likely to intensify into a severe cyclonic storm.
The IDPs at particular risk are mostly stateless Rohingya Muslims uprooted by two outbreaks of deadly religious violence since June last year.
"There are people still living in temporary tents. Now we are moving as many of those IDPs as we can to stronger permanent shelters," said Myo Thant, a spokesman for the Rakhine state government.
He said he was unsure of the capacity of the shelters - located in the state capital Sittwe - but acknowledged there were not enough to accommodate all of the displaced people. "The rest will be sent to stay with relatives in villages, and to nearby school buildings," he said.
The alerts revived memories of Cyclone Nargis, which devastated Myanmar's Irrawaddy Delta in May 2008, killing about 140,000 people.
The UN's disaster assessment agency said preparations were under way to provide shelter for up to 13,000 displaced people in Sittwe, voicing concern for IDPs living in "poorly constructed camps".
"Many of the camps are located in low-lying coastal areas susceptible to tidal surge," it warned.
Myanmar views its population of 800,000 Rohingya as illegal Bangladeshi immigrants and denies them citizenship.