JALPAIGURI (WB): A powerful bomb hidden at a petrol pump in Phuntsholing in Bhutan exploded on Saturday seriously injuring four persons, including three Indians and one Bhutanese national, officials said.

The Indo-Bhutan border had been sealed soon after the blast and the Royal Bhutan government had closed all entry gates to the Himalayan kingdom, they said.

Officials said the blast occurred between 6.30 am and 6.45 am in a waste bin at the Bhutan Gate petrol pump adjacent to the Royal Bhutan Revenue department office in Phuntsholing, 200 metres from the Indo-Bhutan border adjacent to bordering town of Joygaon in West Bengal's Jalpaiguri district.

Three injured Indian nationals are being evacuated to the Binaguri army hospital in Jalpaiguri district, they said.

High police officials from North Bengal have rushed to Joygaon, they added.