At least 32 people have been killed in a blaze on a passenger train in southern India.

One of the coaches of the Tamil Nadu Express caught fire at around 04:20 local time (22:50 GMT) when it was passing through Nellore station in the south Indian state of Andhra Pradesh. Most of the passengers were still asleep and were caught unawares as smoke and flames engulfed the coach. The train, emanating from the capital New Delhi, was bound for Chennai, formerly known as Madras, also in south India.

The S-11 coach which carried 72 passengers was gutted in the incident. Rescue crews used special equipment to save trapped passengers.

The exact cause of the tragedy is yet unknown but an electrical short circuit is suspected to have triggered the fire. The wrecked coach was detached from the train and the remaining passengers were accommodated in other compartments and taken to their destination.

"Inflammable materials being carried by some passengers could have been responsible for the fire spreading rapidly across the passenger coach," said Indian Railways spokesperson Chandralekha Mukherjee.

The death toll is likely to increase as many were battling for their life in a nearby hospital.

Many passengers managed to escape by jumping off the burning train. Most of the victims belonged to Chennai.

"We were travelling in S-12 [next to the burnt coach]. I heard people screaming from nearby compartments. We tried to escape but all doors were locked... Someone pulled the chain and the train stopped," Ahmed, one of the passengers told the Indian daily The Hindu.

India has one of the largest railway networks in the world. Around 18 million people use the Indian railways every day. Up to 1,200 people have been killed in train accidents in India since 2007.

Indian Prime Minister Manmohan Singh expressed his condolences for the victims and urged the railway ministry to take necessary measures. The government announced monetary assistance to all the people affected by the tragedy.