As Nandigram seethed over the land acqusition issue, tension ran high in Singur on Monday night after a few unidentified men exploded four bombs at Beraberi Purbapara village under Singur police station near the Tata's small car project site.

Admitting that the bombs were hurled, Chandannagore SDPO Kalyan Mukherjee said the incident occurred at around 2130 hours in the sleepy village of Singur in West Bengal's Hoogly district.

On receiving the information, a big contingent of police led by the SDPO himself, rushed to the spot but found nobody.

"So far we are clueless about who hurled the bombs. The investigation is on and police personnel have been posted there," Mukherjee said.

However, Mukherjee said the spot where the bombs were exploded was outside the fenced area of the proposed project.

Some members of the Singur Krishi Jomi Raksha Committee, opposing the land acqusition, however, alleged that the security men guarding the fence area were involved in the incident.

The government had acquired a total of 997 acres of farm land for the proposed project that created an outcry from the opposition leading to a mass movement.

The area witnessed violence early last month when a section of villagers clashed with police during the fencing of the acquired land.