Mumbai: At least six persons were killed and scores others were injured as fresh violence erupted in Nandigram as villagers, protesting against land acquisition fought pitched battles with police.

State police chief A B Vohra told reporters in Kolkata that six bodies had been found and the death toll could rise as reports on the violence were yet to be received from different areas.

Unofficial reports put the death toll at over 10, with the ruling Left and its partners saying it could be between 10 and 13, and the Opposition Trinamool Congress claiming 20 people were killed.

Trouble started in the morning when a large contingent of security forces tried to enter various villages in Nandigram area. Protesters under the Bhumi Ucched Pratirodh (Land acquisition resistance) Committee put up a stiff resistance, forcing police to open fire.

Police had to open fire after teargas shells failed to control the situation, said superintendent of police G A Srinivas who was supervising the operation. He said clashes occurred when policemen tried to enter the villages of Bhangabera, Maheshpur and Kalicharanpur, which had been inaccessible to the security personnel since early January when violence had first happened.

Vohra said 25 people were arrested and eight improvised arms, including pipe-guns and ammunition, were seized from Sonachura and Adhikaripara under Nandigram block where patrolling by police has been intensified.

Inspector-general of police (law and order) Raj Kanojia also expressed ignorance about casualties and said police had to resort to firing after teargas and lathi-charge failed to quell violence.

Reports said 14 policemen were injured in the violence and the condition of four was critical while one has been shifted to Kolkata.

The injured included additional SP, Tamluk, circle inspector (Mahisadal) and an IPS probationer from Purulia, reports added.

Nandigram has witnessed violent protests in the wake of reports that land would be acquired in the area for a SEZ to be set up by Indonesia's Salim Group. Police have been prevented from entering villages by people who dug up roads.