A senior police officer said the members of Janashakthi group, including Rajanna, had gathered at the residence of Mohan Reddy, seeking to rebuild the party and establish dalams (armed squads), besides procuring arms and collecting funds.
They have been booked under sections 121A (sedition) and 120B of the Indian Penal Code.
Maoist literature and other documents were recovered from them, said Kurnool Superintendent of Police AK Ravikrishna.
As many as 46 members of CPI(ML) Janashakthi had surrendered before the Andhra Pradesh police in 2002.
The group had been held responsible for several murders and other incidents of violence in the united Andhra Pradesh in the past.