At least 14 people were killed and 75 others injured as people opposing the acquisition of farm land for industries fought pitched battles with police who entered villages here after a gap of about three months to restore law and order.

Home Secretary P R Roy told reporters in Kolkata that 11 people were killed and 75 injured when police opened fire on a mob of about 5,000 villagers who tried to prevent their entry into villages.

Roy said the toll might go up as a search was on for more bodies in the area.

Among the injured were 12 policemen. Twenty people were arrested in connection with the violence.

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.

He 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.

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.

The bodies were sent for autopsy.

Vohra said a strong police force had been rushed to the violence-hit areas and the IGP (Western Range), Superintendent of Police and senior officers were camping at Nandigram.

Patrolling was intensified in the villages at Nandigram, and police were trying to enter interior areas and convince people that they needed to be there to restore law and order, he said.

To a question, Vohra said the imposition of prohibitory orders in the area depended on the situation. "We are closely monitoring the situation."

He also said an intelligence report had indicated that there would be resistance against the entry of police to the villages. There were fewer injuries as the policemen were wearing bulletproof jackets, he added.

Tension has been building in Nandigram since December last year, when reports that the state government would acquire farm land for a SEZ and a chemical hub to be set up by Indonesia's Salim Group sparked protests.

The protests fuelled clashes between a Trinamool Congress-backed group and CPI-M activists, leading to six deaths on January seven. Exactly a month later an intelligence officer was lynched when police tried to enter Nandigram.