At least 60 people were killed and more than 120 people were injured today when a powerful explosion rocked a railway station in eastern India, railway officials and domestic news agencies said.

Railway officials put the death toll at 60 and said 120 were injured in the explosion that tore through Gaisan station, a small-town rail stop in West Bengal state, 300 miles north of Calcutta. The Press Trust of India (PTI) news agency said 70 people were killed and 135 injured.

The Brahmaputra Mail train was passing by the Gaisan platform and another train, the Awadh-Assam Express, was stationary when the blast took place, PTI said. The engine of the Awadh-Assam Express was thrown across to the next track by the blast, PTI reported.

The exact cause of the explosion was not immediately known, but Indian intelligence officials said they suspected northeast Indian separatists who have been linked to Pakistani intelligence agents.

"We had prior information about the movement of such elements in that area and possible attacks," an intelligence official, who asked not to be identified, told Reuters in Guwahati.

Indian media has been reporting growing links between the United Liberation Front of Assam (ULFA) and Pakistani intelligence agents in the northeastern region. Assam is a neighboring state in eastern India.

West Bengal state has been largely isolated from the violence in the hilly northeast, where several rebel groups are fighting New Delhi's rule. But there has been an increase in violence in the region this year. On June 22, nine people were killed in an explosion at a station in New Jalpaiguri, 50 miles from the site of today's blast. But the ULFA, which is seeking Assam's independence, denied any involvement in that incident.