A CBI statement said the probe agency has "registered a case on the request of the Rajasthan government and further directions from union government and taken over the investigation" of the case.
Earlier on June 10, a first information report was filed against Gehlot, Congress state unit president Pilot and six others in Ashok Nagar police station here on allegations of a scam in the running of the 108 ambulance service.
Police after conducting an inquiry into former Jaipur mayor Pankaj Joshi's complaint of July 31, 2013 decided to register a case against Gehlot, Pilot and others on charges of cheating and dishonesty, forgery of valuable security and forgery for purpose of cheating and party to a criminal conspiracy among others.
Joshi had alleged financial irregularities in operating '108' ambulance service during the previous Congress government.
The ambulance service is a part of the National Rural Health Mission and is a public-private partnership to ensure help for emergency patients.