The CBI on Wednesday began its probe into 18 cases referred to it by the Rajasthan Government for alleged irregularities in land deals in Bikaner by companies, including one linked to Robert Vadra.

CBI sources said the agency has re-registered 18 FIRs in connection with these land deals, which were earlier probed by the Rajasthan Police.

"The cases pertain to fraudulent and fictitious claims and allotments in lieu of land acquired for Mahajan Field Firing Range Bikaner, which is used by the Army," a CBI spokesperson said here after the cases were registered this evening.

Among the 18 FIRs registered by the agency, 16 were lodged at the Gajner police station while two at Kolayat police station in Bikaner between August and September, 2014, agency sources said. The cases were referred to the CBI by the Centre on the request of the Rajasthan Government.

The Rajasthan Government had written to the CBI for a probe into alleged land scams in Bikaner, including those involving a company linked to Congress president Sonia Gandhi's son-in-law Robert Vadra.

The Congress had accused the State Government of misusing the CBI ahead of Assembly elections.

"As many as 18 FIRs are registered. Four of them are against Vadra's company which were allegedly involved in illegal purchase of nearly 275 bigha land. All the 18 FIRs are in connection with the purchase of close to 1,400 bigha land in fake names," Rajasthan Home Minister Gulab Chand Kataria had said on August 22 after referring the matter to the CBI.

He had alleged that Vadra's company was the third party to purchase 275 bigha of land in 2010 and it sold it to a fourth party in 2012.