Kolkata, May 8 : The Central Bureau of Investigation (CBI) on Monday replaced the head of its Special Investigation Team (SIT) probing the alleged multi-crore recruitment scam in state-run schools in West Bengal. CBI officer Dharamveer Singh has been replaced by Kalyan Bhattacharya following the approval of the Calcutta High Court. Singh had sought early retirement from service. In March, the CBI had sought permission from the high court's single-judge bench of Justice Abhijit Gangopadhyay for immediate release of Singh, a superintendent-rank officer. The CBI counsel argued that since the SIT was constituted following the instruction of the high court, the latter's approval for Singh's release was necessary. Justice Gangopadhyay had insisted then that Singh should be replaced by a Bengali-speaking officer of the same rank. On Monday, the central agency has arranged for the replacement of Singh with Bengali-speaking Kalyan Bhattacharya. In November last year, Justice Gangopadhyay had ordered reconstitution of the SIT constituted by the CBI. In that reshuffle, two officers -- one in the rank of deputy superintendent and the other in the rank of inspector -- were replaced, but Dharamveer Singh continued as the member of the team. While ordering reconstitution of the SIT, Justice Gangopadhyay had observed that the reshuffle became imperative to fast-track the pace of the investigation, which, according to him, was extremely slow. /IANS