Ranchi/Kolkata, March 11 (IANS) Backed by air cover, security forces have launched a major campaign against Maoists in the border districts of West Bengal and Jharkhand, officials said Thursday. Orissa will join the drive.

An unspecified number of police and paramilitary personnel are pursuing the guerrillas in a well coordinated operation called Green Hunt that started three days ago, a Jharkhand police officer told IANS in Ranchi on condition of anonymity.

'Initially, the operation was kept a secret,' the officer said.

'The operation has been launched in five bordering districts. The paramilitary forces and state police are sanitising the jungle areas. Some landmines have been recovered and four Maoist camps destroyed.

'The operation has air surveillance. Security forces have made a makeshift helipad in Saranda jungle area (in Jharkhand),' the officer added.

In Jharkhand, the operations are going on in three places, he said, adding that the Maoists are being chased in Purulia and West Midnapore districts in adjoining West Bengal.

But in Kolkata, Inspector General of Police Zulfiqar Husan told IANS that the operation began Thursday and that three districts in West Bengal were covered: West Midnapore, Bankura and Purulia.

'Similar operations are also being carried out in Jharkhand,' he said.

According to him, three helicopters were used for aerial surveillance all over the area.

Said another official: 'The move is to zero in on Maoists in bordering areas.'

West Bengal and Jharkhand are among half a dozen states most acutely threatened by Maoist violence. The other states include Bihar, Orissa, Chhattisgarh and Madhya Pradesh.

Vijay Raman, the special director general of the Central Reserve Police Force (CRPF), Wednesday met the Jharkhand police chief here to reportedly discuss the inter-state operations against Maoists.

On Feb 9, Home Minister P. Chidamabram met the chief ministers and top officials of Bihar, Jharkhand, West Bengal and Orissa, reportedly to give a final shape to the anti-Maoist drive.