CHENNAI (AFP) - A special 50-wagon train carrying 2.5 million litres of water arrived in the Indian city of Chennai on Friday (July 12), as the southern hub reels under one of its worst shortages in decades.

The wagons were hauled by a special locomotive, decorated with flowers and with a "Drinking Water for Chennai" banner on its front.

Four special trains a day have been called up to bring water to Chennai - India's sixth most populous city - from Vellore, some 125km away, to help battle the drought.

The first consignment will be taken to a water treatment centre, and then distributed in trucks to different parts of the metropolis on Saturday (July 13).

Chennai has seen only a fraction of the rain it usually receives during June and July.

The city of 4.9 million people also needed trains to bring water in when it suffered a similar crisis in 2001.

The bustling capital of Tamil Nadu state normally requires at least 825 million litres of water a day, but the authorities are currently only able to supply 60 per cent of that.

With temperatures regularly hitting 40 deg C, reservoirs have run dry and other water sources are dwindling further each day.

The Chennai metro has turned off its air-conditioning, farmers have been forced to stop watering their crops, and offices have asked staff to work from home.

The city's economy has also taken a hit as some hotels and restaurants shut shop temporarily, and there have been reports of fights breaking out as people queue for water.