The state government has issued an alert to police chiefs of Patna, Jehanabad, Arwal, Aurangabad, Nawada and Gaya districts, fearing a backlash from the supporters of Brahmeshwar Singh, who was shot dead by unidentified men June 1.

Brahmeshwar Singh, popularly called Mukhia by his supporters, was killed by gunmen in Ara town, about 60 km from here, while on a morning walk. In 1994, he set up the Ranvir Sena, an upper caste private militia which has been blamed for many killings.

The alerted districts were the strongholds of the Ranvir Sena and its rivals - outlawed Maoist groups and the Communist Party of India-Marxist Leninist (CPI-ML) - till early 2000.

According to officials in the police headquarters here, police patrolling has been intensified in rural areas dominated by CPI-ML and Maoists.

"Police officials have been directed to keep a close vigil on Ranvir Sena leaders and activists," a police official said.

According to officials, most of the massacres by the Ranvir Sena and counter massacres by Maoists took place in these districts.

"All these districts are considered sensitive and attack by supporters of the Ranvir Sena chief on Dalits and backward castes cannot be ruled out," a police official said.

An intelligence report has warned the state government that angry supporters of Brahmeshwar Singh held a secret meeting after his killing.

The Bihar government has recommended a Central Bureau of Investigation (CBI) probe into his killing.

A five-member special investigation team (SIT) of Bihar Police is probing the June 1 killing that sparked widespread violence in the state.