Cyclone Mocha was gaining strength and set to intensify into a very severe cyclonic storm by Friday morning, packing winds of up to 135 kmph, and likely to move towards the Bangladesh-Myanmar coast, the weather office said on Thursday night.

At 5:30 pm, the cyclonic storm lay over south-east Bay of Bengal, about 520 km west of Port Blair and 1,100 km south-southwest of Cox's Bazaar, a fishing port in Bangladesh, the India Meteorological Department said.

The weather office said Cyclone Mocha (pronounced Mokha), named by Yemen after its Red Sea port city, will further intensify on Friday and re-curve north-northeastwards for a Sunday landfall between Cox's Bazaar and Kyaukpyu, close to port city Sittwe in Myanmar, packing winds of 175 kmph.

The weather office has asked fishermen, ships, boats and trawlers not to venture into central and northeast Bay of Bengal and north Andaman Sea till Sunday.

Those sailing in central Bay of Bengal and north Andaman Sea are advised to return to coast.

The IMD predicted a storm surge of 1.5-2 metres for the low-lying coastal region of Bangladesh near Cox's Bazaar.

Under the influence of the weather system, Tripura and Mizoram are likely to get heavy rainfall Saturday onwards. Nagaland, Manipur and south Assam are expected to get rainfall at many places on Sunday.