Security has been tightened on the trains running in the region

The rebels stopped a train in a remote area in Jharkhand state on Monday evening and held the passengers captive for more than 12 hours.

The rebels freed the passengers early on Tuesday and left the area.

More than 6,000 people have died during the rebels' 20-year fight for a communist state in tribal areas of India, including Jharkhand.

Jharkhand is rich in minerals and forest resources, but its people are among the poorest in India.

It appears they [rebels] wanted to prove a point SK Sone, Jharkhand official

Senior local official SK Sone told the Associated Press news agency that the rebels had left the area by the time authorities arrived at the scene on Tuesday.

"It appears that they just wanted to prove a point that they could do such a thing," he said.

None of the passengers had been hurt after the rebels stopped the train in Latehar, some 1,200km (750 miles) south-east of the Indian capital, Delhi.

'Battle against government'

Jharkhand police chief DK Pande told the BBC that the train driver had run away from the scene after the rebels fired in the air.

Superintendent Subodh Kumar said the rebel leaders had told the passengers that they did not have "anything against you and therefore you are free to go".

"This battle is against the government," Mr Kumar said, quoting a passenger.

Mr Kumar said the rebels tried to set the engine on fire after ordering all the passengers out of the train.

"Many women and children are crying, they must be terrified after being held captive all night, but thankfully the ordeal is over," he said.

The rebels have been active in Jharkhand state for several years.

Last October at least 12 paramilitary soldiers were killed in a mine blast which was blamed on the rebels.

The authorities say the guerrillas killed at least 13 villagers who had formed self-defence group to counter them last September.