The deep depression over the southwest Bay of Bengal and the adjoining areas has intensified into a cyclonic storm 'Nivar.'
It is likely to intensify further and move in the northwesterly direction.
It was centred about 1,665 kilometres southwest of Chittagong port, 1,610 km southwest of Cox's Bazar port, 1,555 km southwest of Mongla port and 1,550 km southwest of Payra port at 6:00 am on Tuesday, said a Met office press release.
Maximum sustained wind speed within 54 km of the depression centre is about 62 kilometres per hour rising to 88 kmph in gusts or squalls.
Sea will remain very rough near the cyclone centre.
Maritime ports of Chattogram, Cox's Bazar, Mongla and Payra have been advised to watch carefully for further necessary instructions.
All fishing boats and trawlers over North Bay have been advised to proceed with caution.
The storm might hit the coasts of Tamil Nadu and Puducherry in India on Wednesday (November 25).
It has already started raining in the coastal states of South India since November 23.
Meanwhile, Abdur Rahman, a senior meteorologist at Bangladesh Meteorological Department, said the cyclone would not be a problem for Bangladesh.
Iran has named the cyclone Nirvar.