The rebels have also abducted four policemen in the past one week, two of whom still remain untraced.

Lalgarh, about 200 kms west of Kolkata, has been on the boil since November last year when a landmine exploded on the route of the convoy of Chief Minister Buddhadeb Bhattacharjee and two then central ministers -- Ram Vilas Paswan and Jitin Prasada.

Alleging police atrocities after the blast, the Maoists, alongside the PCAPA, launched an agitation and made the area a virtual 'free zone' by torching police camps and offices of the ruling communists and driving out the civil administration.

Maoists are active in areas under 21 police stations in the state's three western districts - West Midnapore, Bankura and Purulia.