The CBI today raided about 10 premises in the National Capital Region after it registered a fresh FIR in connection with its probe into the alleged multi-crore Commonwealth Games overlays scam.

The raids come a day after the agency questioned Commonwealth Games Organising Committee chief Suresh Kalmadi.

Official sources said the CBI registered the FIR, the fourth in the case, yesterday in connection with the overlays contracts given out to four firms. The total value of these contracts was over Rs 600 crore.

The sources said the CBI raids started early in the morning and are focussed on four companies, which had acted as the Indian arm for the same number of international firms.The contracts were bagged by consortium of foreign and Indian firms.

While the details of the FIR are still to be known, the sources said involvement of some OC officials could be probed.

The overlays contracts are already under the scanner of both the Income Tax Department and the Enforcement Directorate.

The CBI had earlier registered three FIRs for alleged corruption in projects and events in the run up to the sporting extravaganza.

While two cases have been registered in connection with alleged irregularities in the Queen's baton relay, the third FIR is in connection with the awarding of contract for time and scoring.