Social activist Swami Agnivesh will be present at the rally.
DGP Bhupinder Singh said: “I can’t share specific information for security reasons. There is a strong possibility of armed Maoist squads sneaking into Lalgarh (160 km west of Kolkata) and adjoining areas with the rally on August 9. They will then target police installations.”
August 9 is a significant date in history. In 1942, the Quit India Movement started on this day and the atom bomb was dropped on Nagasaki in Japan three years later.
Trinamool sources said more than 100,000 party supporters were expected to arrive in Lalgarh from neighbouring areas in East Midnapore and districts such as Bankura and Purulia.
“It will be virtually impossible for us to stop them (Maoists) on that day,” a police officer said.
Chief Minister Buddhadeb Bhattacharjee expressed misgivings about the rally on July 22, a day after Railway Minister Mamata Banerjee announced the event in Kolkata.
The Maoists in Bengal have been under pressure because the security forces have killed two top PCAPA leaders.