The CBI had taken over investigation into the case on August 30 night on request of Karnataka government

The CBI has questioned senior IAS officer Rajkumar Khatri, the Karnataka revenue secretary, in connection with a ponzi scam allegedly perpetrated by I-Monetary Advisory (IMA) which duped investors promising higher returns using Islamic methods, officials said Friday.

They said Khatri came at the agency office in Bengaluru recently where his statements were recorded by the CBI team probing the matter.

The agency on Thursday questioned former Karnataka minister Zameer Ahmed Khan in connection with the scam.

The agency is continuing questioning of Khan whose CBI custody was extended Friday for four more days.

The CBI had taken over investigation into the case on August 30 night on the request of the Karnataka government, routed through the Centre, they said.

It is alleged that lakhs of gullible investors fell in the trap of higher returns using Islamic methods of banking offered by IMA and its subsidiaries and deposited their savings.

The company started defaulting on payment in spite of repeated reminders from the investors, the CBI has alleged in the FIR registered by it on August 30.

"It was alleged that the founder director (Khan) of group of entities based in Bangalore had illegally collected deposits from the public in the form of investments on various ponzi schemes such as monthly plan, education plan, marriage plan, etc., with a promise of getting high returns," a CBI spokesperson had said after the FIR.

The lid went off the scam when Khan fled to Dubai, leaving behind a video message, saying that he was committing suicide because of "corruption in the state and central governments".