Kolkata, Jul 7 (IANS): Police in West Bengal has seized more than 100 live crude bombs and arrested nine persons for keeping illegal arms, police said on Sunday.

Police intensified vigil across Birbhum, a district with a long history of political violence, after two separate blasts took place in Mallarpur and Labhpur here within a span of 10 days.

Though no one was killed or injured in the blasts as they took place in empty buildings, the incident brought back grim memories of the 2017 blast that had killed eight persons.

"We have seized over 100 live bombs from different areas in Birbhum. The bomb defusal squad personnel have successfully defused the bombs. Nine persons have been arrested and six illegal firearms have been seized from them during night-long raids across the district," Birbhum Police Superintendent Shyam Singh told IANS.

"We have arrested three persons in the Labhpur blast case. Further investigation is underway," he said.

When asked whether explosives and illegal arms are being brought in from outside Bengal, the officer refused to comment but said such incidents of blasts and violence "are not new in Birbhum".

A blast ripped through a club building near Mallarpur railway station in the wee hours of June 30, causing the roof and a wall of the building to partially collapse. Forensic team was called in to ascertain the nature of the blast.

On July 4, another blast in Birbhum's Labhpur rocked an abandoned section of a government primary health centre, close to a district police camp. The blast took place around 3 a.m. and caused the debris to flung over 20 meters away, damaging the roofs of two nearby buildings.