Khan was questioned about the purchase of a high-end car in 2004 and the mode of the transaction and requisite supporting documentation, which the ED suspects to have contravened the Foreign Exchange Management Act (FEMA).
Sources close to the actor said he was quizzed by the agency with regard to some documentation of his residential bonafides and they are cooperating with the investigators.
The ED, according to sources, is probing if the payment for the vehicle which was imported from abroad was made through illegal channels known as 'hawala' and if it complied with FEMA rules.
The ED has been probing the case for sometime and they will complete the investigation soon.
Khan has submitted some documents to the authorities which will be scrutinised, they said.
Khan is the winner of national film award for best actor in 2004 for his role Hindi film 'Hum Tum'.
