The security forces used mine detectors to sweep the roads before driving ahead in heavy vehicles. An IAF helicopter made a sortie over Lalgarh -- where Maoist leaders, including a key functionary Kisanji, are believed to be holed up -- dropping leaflets asking the people not to allow themselves to be used as human shields. 

The tribals under the People's Committee Against Police Atrocities blocked the passage to Lalgarh by felling trees and digging up roads and blowing up a bridge at Binpur, 12 km from Lalgarh.

Roads at Dahijuri and Dherua were dug up and trees felled to obstruct the advance by armed police and Central security forces, while a bridge over a river at Binpur was blown up, the police official said.