The Siwan jail turned into a virtual battle ground on Tuesday as RJD MP Mohammad Shahbuddin and his supporters clashed with a rival group inside the jail premises. More than two dozen inmates and policemen, including the Jail Superintendent, were injured in the clash. Siwan District Magistrate Santosh Kumar Mal said an FIR has been lodged against Shahabuddin and 11 others in this regard. The clash led to the addition of one more case against the dreaded RJD MP, who is already being tried in more than two dozen cases. He has been convicted in one of them. The police had to resort to lathicharge for around 20 minutes to control the situation, the DM said. Trouble began in the afternoon when Shahbuddin summoned three other inmates to his room. As they refused to obey him, his supporters started beating them. Soon the jail inmates got divided into two groups and started pelting stones at each other. The Siwan District magistrate said that security has been beefed up inside the premises. “We are also planning to shift a few prisoners to some other jails for security reasons,” he said.