A deep depression over the Bay of Bengal has intensified and could develop into a cyclone.
The Bangladesh Meteorological Department forecast further strengthening and a possible landfall on India's Andhra Pradesh coast as a very severe cyclonic storm.
If it forms, the cyclone will be named Arnab, a name proposed by Bangladesh that means ocean or sea.
Thirteen countries in the World Meteorological Organisation's North Indian Ocean region, covering the Bay of Bengal and the Arabian Sea, participate in the cyclone-naming process. They are Bangladesh, India, Iran, the Maldives, Myanmar, Oman, Pakistan, Qatar, Saudi Arabia, Sri Lanka, Thailand, the United Arab Emirates and Yemen.
In a special bulletin issued on Sunday, the Meteorological Department said the deep depression was centred 810km south of Chattogram Port, 730km south of Cox's Bazar Port, 850km south of Mongla Port and 780km south of Payra Port at noon.
The system could move further north-westwards and intensify into a cyclone on Monday, the department said.
It may subsequently change direction and head towards the West Bengal–north Odisha coast before potentially crossing India's Andhra coast as a very severe cyclonic storm by Wednesday.
The department said highest sustained winds within 48km of the depression's centre were reaching 50km per hour, with gusts or squalls of up to 60km per hour. The sea was rough near the centre.
In view of the situation, Chattogram, Cox's Bazar, Mongla and Payra ports have been advised to keep hoisting distant warning Signal No. 1.
All fishing boats and trawlers in the northern Bay of Bengal have also been instructed to move closer to the coast and navigate with caution until further notice.