The incident happened minutes after the express train entered the station.  One woman has been killed and nine others injured in a bomb attack aboard a train at a station in the southern Indian city of Chennai, officials say.

Explosions were reported in two carriages of the train, which was travelling from Bangalore in the south to Guwahati in the north-east.

The incident happened minutes after the express train arrived at the station.

The blasts come in the middle of India's staggered general election, but officials say they cannot confirm if the two events are linked.

Some Indian television channels are speculating about who may have been behind the attack, but the authorities say they are keeping an open mind

There have been relatively few incidents of violence in these elections so far, but this attack is bound to cause alarm as India heads into the last two rounds of voting, our correspondent adds.

Chennai police chief JK Tripathi said Thursday's blasts could have been triggered by "a basic mobile device".

Television pictures showed a hole blown through the floor of one coach, injured passengers being helped away and scores of policemen on nearby tracks beginning an investigation.

"A young lady, aged 22, has lost her life. There were two separate blasts in the train. The entire police force is involved in the investigation," senior railway official Rakesh Mishra said.

Chennai (formerly known as Madras) in Tamil Nadu state is one of the busiest railway stations in southern India, as thousands of commuters use it every day to travel to neighbouring cities and states.