Bangladesh has ordered the evacuation of hundreds of thousands of people from its coastal areas threatened by Cyclone Mahasen.
The Bangladeshi authorities have raised the danger level to seven out of 10 for low-lying areas around Chittagong and the coastal district of Cox’s Bazar.
The cyclone, heading north-east through the Bay of Bengal, is estimated to reach land on Thursday.
Burma is also threatened and evacuation efforts are under way there.
Tens of thousands of Rohingya Muslims living in camps in low-lying areas of Burma’s Rakhine state are feared to be at risk.
Bangladesh has ordered the evacuation of hundreds of thousands of people from its coastal areas threatened by Cyclone Mahasen
They were displaced by ethnic violence last year and many are reluctant to move from the camps.
The country’s National Planning Minister, Tin Naing Thein, said more than 150,000 people had been relocated to higher ground. The government said a fifth of those were Rohingyas.
The Bangladesh Meteorological Department said the storm could create a surge 2 m high in coastal districts and residents are being urged to make for cyclone shelters.
The airport in Cox’s Bazar has closed and Chittagong airport is to shut over the next few hours.
The United Nations Office for the Co-ordination of Humanitarian Affairs said Cyclone Mahasen appeared to have weakened to a Category One storm.
But the UN still described it as “life-threatening” for 8.2 million people in Bangladesh, Burma and north-east India.
At least 50 Rohingya Muslims were feared drowned on Tuesday when boats evacuating them from the path of the cyclone capsized off western Burma.
More than 100,000 people died in 2008 when Cyclone Nargis devastated many of Burma’s coastal villages.
At least 56 people have been killed and hundreds of homes torched since Sunday, as clashes spread in Burma’s Rakhine state.
Several were killed overnight as violence erupted despite a night-time curfew in at least two towns.
The latest clashes are the first serious outburst of violence since June when a state of emergency was declared in Rakhine after 90 people were killed.
But tensions remained high between ethnic Rakhine Buddhists and Muslims.
It is unclear what prompted the latest clashes. The Rakhine Buddhists and Muslims blame each other for the violence.
Clashes erupted in the Ratha Taung township late last night but this later spread to the Kyauk Taw township, where security forces opened fire, reports say.
Rakhine state spokesman Win Myaing said on Thursday that the total death toll since violence flared up again on Sunday had reached 56.
More than 1,000 houses have been torched since then and police have deployed reinforcements in the townships of Min Bya and Mrauk Oo, where curfews are now in effect.
It was the rape and murder of a Buddhist woman by three Muslims in May that set off the initial unrest.
A mob later killed 10 Muslims in retaliation, although they were unconnected with the earlier incident, and the violence escalated after that.
In June, about 90 people were killed as clashes spread across the state.
The houses of both Buddhists and Muslims were burnt down and thousands of people fled. Muslims throughout Burma have abandoned plans to celebrate the festival of Eid al-Adha because of the violence.
There is long-standing tension between the ethnic Rakhine people, who make up the majority of the state’s population, and Muslims, many of whom are Rohingya. The Burmese authorities regard the Rohingya as illegal immigrants and correspondents say there is widespread public hostility to them.
In August Burma set up a commission to investigate the violence between Buddhists and Muslims in the west of the country. Authorities earlier rejected an UN-led inquiry.