The arrest was made in Switzerland yesterday on the request of Italian authorities probing allegations of bribery in the contract for 12 VVIP helicopters.
Haschke, who is among 13 accused booked by CBI in connection with the corruption case, will be extradited to Italy next week.
Also Read
Highly placed CBI sources said the letter has been sent to the Indian embassy seeking details on his custody and the ongoing probe. The agency will also be sending a judicial request to Italy for detailed information on the statements given by the accused who are in the custody of the authorities there.
They said after getting the statements, the agency would explore the option of seeking extradition of all the accused who are in the custody of Italian authorities. However, at the moment, there is no such move, they said.
The helicopter contract is under probe of Italian and Indian agencies for alleged kickbacks paid to Indian officials - including former IAF chief S P Tyagi - to clinch the deal.
Tyagi has denied allegations of any kickbacks.
Swiss-American Haschke is one of the 13 accused named in the FIR filed by CBI which is probing the bribery allegations in the deal.