Chennai/IBNS: A deep depression has formed over the Bay of Bengal, which has intensified into a cyclone named Fengal and is likely to cross the Tamil Nadu coast between Karaikal and Mamallapuram on Saturday, the India Meteorological Department said this evening.

The cyclone is expected to carry winds at 70-80 km per hour with gusts up to 90 kph.

"The deep depression over southwest Bay of Bengal moved north-northwest at 13 kph in the past six hours (and has) intensified into Cyclonic Storm Fengal... at 2.30 pm (on November 29) it lay 270 km east-southeast of Puducherry and 300 km southeast of Chennai," the IMD said.

"It is likely to move west-northwest and cross north Tamil Nadu and Puducherry coasts between Karaikal and Mamallapuram (but closer to Puducherry) as a Cyclonic Storm..."

Chennai Meteorological Centre director Dr S Balachandran warned of moderate rainfall over northern Tamil Nadu and coastal districts. Some places are likely to receive heavy to very heavy rainfall.

One or two places will also receive extremely heavy rainfall, he said.

The government has advised fishermen to not venture into the Bay of Bengal till further notice.

Across Tamil Nadu, Chennai, Tiruvallur, Chengalpattu, Kanchipuram, Viluppuram, Kallakurichi, and Cuddalore districts have been placed on red alert, as has Puducherry.

An orange alert is in place in Ranipet, Tiruvannamalai, Vellore, Perambalur, Ariyalur, Thanjavur, Tiruvarur, Mayiladuthurai, Nagapattinam, and Karaikal districts.

Interior districts have also been warned of rainfall as Fengal moves inland after Sunday.

The impact of Cyclone Fengal has already started in the southern state.

Ahead of the impact, Chennai is experiencing high tides and gusty winds.

On Thursday, heavy rain caused widespread damage to paddy crops across 800 acres in Nagapattinam district while the threat of heavy rain prompted schools and colleges in the Chennai, Chengalpattu and Cuddalore areas to shut on Friday.