Siwan superintendent of police Saurav Kumar Sah and district magistrate Mahendra Kumar carried out the surprise inspection at the Siwan Central Jail to find out whether there was violation of jail manual or not.
As many as 38 mobile phones were seized from some of the visitors, the Superintendent of Police said.
Sah said that it was found that an unsually large number of visitors had gathered at Siwan Central Jail to meet the prisoners lodged there which amounted to violation of jail manual.
The SP denied that the security audit has had anything to do with the ongoing investigation in the journalist Rajdeo Ranjan case in which RJD strongman Md Shahabuddin's role has been alleged by the family members and the opposition.
Ranjan, the bureau chief of a vernacular daily, was shot dead by unidentified gunmen in Siwan town on Friday last.
Under severe attack from the opposition for lawlessness in Bihar, the state government has recommended for a CBI probe in the journalist murder case.