The CBI on Thursday arrested Kalyanmoy Ganguly, a former president of the West Bengal Board of Secondary Education, in connection with the Group-C recruitment scam case in government schools, officials said.

They said that Ganguly was called for questioning at the agency's Kolkata office and taken into custody after he was found non-cooperative.

The arrest triggered a war of words between the TMC and the BJP, with the latter claiming that the investigators would soon reach the doorsteps of the top echelons of the ruling party.

The officials said the Central Bureau of Investigation (CBI) had registered the case on May 20 against five accused, including Ganguly.

It is alleged that the accused extended undue advantage to undeserving and unlisted candidates for the posts of Group-C staff in various schools across West Bengal in a criminal conspiracy with each other.

"The aforesaid persons collected the vacancies of Group-C in an unauthorised manner after the expiry of the panel on May 18, 2019, in violation of provisions of School Service Commission Rules, 2009," the FIR alleged.

The officials said the accused issued recommendations of unsuccessful candidates for those vacancies by issuing fictitious memos of regional commissions and using scanned signatures of the chairpersons of such commissions without their knowledge.

"On the basis of these recommendations, appointment letters were issued, bypassing the normal chain of hierarchy and without sending those recommendation letters to the appointments section of the Board of Secondary Education, West Bengal and without notifying the names of the candidates on the website of the Central Commission for verification of testimonials and collection of appointment letters on the notified date," the FIR alleged.

The BJP attacked the ruling party over the arrest of Ganguly.

"The arrest proves that the TMC government is neck deep in corruption. The TMC might try to wash its hands off, but the day is not far away when the entire ruling party's top brass would be behind bars," BJP state president Sukanta Majumdar said.

TMC state general secretary Kunal Ghosh said the law would take its own course, and the party has nothing to say about Ganguly's arrest.

"He was not a member of the TMC. So there is nothing political about it. The opposition parties can say whatever they want to. The TMC will never compromise with corruption," Ghosh said.

Senior CPI(M) leader Sujan Chakraborty welcomed the arrest but wondered why it took the central agency so long to arrest Ganguly.

The former WBSEB president was arrested around two months after former education minister Partha Chatterjee was apprehended by Enforcement Directorate (ED) for his alleged involvement in the scam.

In August, the CBI arrested former advisors of the SSC, Dr Shanti Prasad Sinha, and its ex-secretary Ashok Kumar Saha for their alleged involvement in the SSC scam.