The men, the police said, were using WhatsApp to stay in touch with their contacts in Pakistan. The phones have been sent for forensic tests to discover the contacts and conversation. The police are also trying to establish the locations of the numbers that the prisoners have contacted.
"We got inputs from jail authorities about their suspicion of some mobile phones being operated from inside the jail premises," Nitish Kumar, a senior officer of the local police, told NDTV.
During a joint search on post-midnight today, 20 cellphones, along with SIM cards, chargers, headphones and memory chips and some written codes were found.
A case has been registered and further investigations are on. The spotlight is on the role of jail staff, an officer said.
The police suspect that the jail staff is complicit, since cellphones are banned for inmates under the jail rules. In April, nearly a dozen phones were recovered from the same jail and after an investigation, several jail officials were suspended.