The Hatia and Sandwip sea routes were closed and large ships ordered to leave Chattogram port on Wednesday night as ‘Fani’, now a very severe cyclonic storm, approaches fast.
"Fani" was centred about 1,110km southwest of Chattogram port at 6am on Thursday.
Maritime ports in Chattogram, Cox"s Bazar, Mongla and Payra have been advised to keep local warning signal number four hoisted.
"Fani" is likely to intensify further, the Met Office said.
At an emergency meeting, Chattogram port authorities ordered large ships to leave to avert possible damage while the district"s disaster management committee decided to shut the Sandwip and Hatia sea routes as precautionary measure.
Met Office said the maximum sustained wind speed within 74kms of the storm centre is about 160kph, rising to 180kph.
The government has opened control rooms in 19 coastal districts and kept 56,000 volunteers prepared. Delowar Hossain, the acting deputy commissioner of Chattogram, said they have prepared 2,739 cyclone centres and are warning residents of the coastal areas.