Patna: The income tax department raided 16 offices and residential premises connected to Mentors Eduserv - a coaching institute chain for engineering aspirants - on Tuesday and seized around Rs 70 lakh in cash, several bank passbooks, and voluminous documents related to diverse investments. Four bank lockers were also traced and frozen.

The raids, involving around 200 income-tax personnel, started around afternoon, and were on till the time of going to the press.

Officials said the operation was expected to continue through the night.

Of the installations raided, 14 are branches of a coaching institute, including one at Jamshedpur in Jharkhand, while two are residential premises related to its owner and his brother in Patna.

"The director or proprietor of Mentors Eduserve is A.K. Jaiswal. It is a successful coaching institute with 13 branches in posh areas of Patna and one in Jamshedpur. We had information that the coaching institute was not paying taxes as per its income. So far Rs 70 lakh in cash has been seized, but counting of currency notes is still on," an income tax official connected with the raid told The Telegraph on condition of anonymity.

Income tax authorities said around 15,000 students were enrolled with the coaching institute, but suspected the number could go higher after perusal of all the seized documents.

"Raids are also on at two residential premises of the proprietor and his brother. One residence is located at Khetan Gali on Boring Canal Road, and another at Durga Acropolis in the same locality," the income tax official said.

All the branches of the institute were shut for the day as raids continued. Students sitting in class rooms were asked to leave.

Sources said that though the coaching institute was a successful one, it did not have proper seating arrangement for students. Those enrolled had to suffer cramped conditions with up to 400 boys and girls being made to sit in one classroom.