Cyclonic storm ‘Titli’ in Bay of Bengal has further intensified, turning into Severe Cyclonic Storm on Wednesday as it heads to the coasts prompting Bangladesh authorities to shut river transports across the country.

The Met office has said Titli has intensified to a ‘severe cyclonic storm with the core of hurricane’.

It has advised cautionary signal No. 4 for the maritime ports in Chattogram, Cox's Bazar, Mongla and Payra as the sea will be rough due to the cyclone.

Cautionary signal 4 means the ports will be affected by the cyclone with a probable wind speed of 51kph to 61kph. Highest security measures are yet to be needed.

The cyclone centred  880km south-west of Chattogram port, 850km south-west of Cox’s Bazar port, 720km south-west of Mongla port and 740km south-west of Payra port at 6pm on Wednesday, the Met office said in a special bulletin.

The maximum sustained wind speed within the 74km of the cyclone centre was about 120kph rising to 140kph in gusts and squalls.

It will affect the Sundarbans, Satkhira, Bagerhat and Khulna, according to meteorologists in Bangladesh.

The cyclone has caused clouds clustering in the sky in Dhaka and some other parts of the country.

It will bring dangerous flooding and gusty winds to parts of India and Bangladesh into the weekend, reports AccuWeather.

“The storm strengthened rapidly on Wednesday, and will continue to strengthen further before making landfall later this week,” it said.

Rain from the storm started to reach the eastern coasts of India on Wednesday, and will become increasingly heavy ahead of landfall on Thursday, says the US-based media outlet, which specialises in weather services.

Conditions in general will worsen through Thursday as the potent tropical cyclone unleashes torrential rainfall and increasing winds on far northeast Andhra Pradesh and Odisha.

The strongest winds will likely be confined to the coasts of northeastern Andhra Pradesh and southern Odisha.

Ahead of landfall, Titli is expected to strengthen to a very severe tropical cyclone, bringing sustained winds of at least 120 km/h (75 mph). This is equivalent to a Category 2 hurricane in the Atlantic and Eastern Pacific tropical basins.