At least five train passengers in India have been killed and four injured after a bomb has exploded under a train carriage in the country's northeast.

The blast hit the Rajdhani Express, bound for New Delhi from Dibrugarh in Assam state, just after a station near Chungajan, T Rabha, a railway spokesman said.

"A car near the luggage van took the whole impact of the blast before dawn Thursday. Five passengers were killed and four others wounded," Rabha said.

The remaining 31 passengers in the affected car were shifted to another car and the train later resumed its journey.

The Rajdhani Express connects India's northeast with the capital. It can carry 900 passengers, but was not running at full capacity, Rabha said.

All of those killed in the blast were migrant workers from Bihar, the Hindustan Times website quoted a police offical as saying.

"We suspect the bomb was planted inside the train from early examinations, but we cannot conclude for sure just now," P Saloi, a police superintendent, said.

Several armed groups, including the separatist United Liberation Front of Asom, are fighting for autonomy or independence in the Assam region, home to 26 million people.

The fighters say India's national government exploits the northeast's rich natural resources while doing little for the area's indigenous people.

PHOTO CAPTION 

File photo shows Indian soldiers standing guard as a train passes in Guwahati, the capital of India's northeastern state of Assam. [AFP]

Al-Jazeera