New Delhi - A bomb rigged to a cycle exploded in India's eastern state of West Bengal Wednesday, killing at least one person and injuring 12 others, news reports said.

The bomb exploded at a busy market in northern Alipurduar town at about 11:10 am (0540 GMT), the IANS news agency reported.

"According to official reports, one person died and 12 others were injured in the blast. The condition of three is serious," West Bengal Inspector General of Police Raj Kanojia told the agency.

The PTI news agency said the explosion was "powerful" and the nature of the explosives was being investigated.

Rebels from separatist outfits including the United Liberation Front of Asom and the Kamtapur Liberation Organisation from the adjoining Assam state are active in the area.

But police said it was too early too say who was behind the blast.

West Bengal's top official, chief secretary Ashok Chakraborty, said there was no relation between the upcoming general elections and the bombing.

"There are no links between the Lok Sabha elections and today's blast. It is not a political incident but work of unidentified terrorists," Chakraborty told a local news channel. (dpa)