Patna district authorities on Tuesday raided the high-security Beur and Phulwarisharif jails after revelation that a person serving a jail term was involved in the abduction of two National Hydel Power Corporation engineers.

The raids were conducted soon after the Delhi-based families of T Mandal and K K Singh received calls demanding Rs 10 crore as ransom.

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The authorities, alarmed by reports of jail inmates running criminal activities in Bihar, detected 'serious violation' of the jail manual during the raids.

Senior Superintendent of Police Nayyar Hasnain Khan, who, along with District Magistrate Gautam Goswami, led the search operation, confirmed that the raids were conducted in connection with the abduction. The authorities detected certain irregularities, including undue favours being bestowed upon a select group of inmates, he said.

Some articles, too, were seized, Khan said, adding the administration had definite information about some inmates' involvement in abductions.