CBI sources said Kul Bhushan was asked to appear at the agency headquarters in connection with the preliminary enquiry, registered soon after bribery scandal involving former Railway Minister Pawan Bansal's nephew had surfaced, which relates to several counts of alleged corrupt practices including purchase of 'benami' properties.
They said Kul Bhushan who arrived at the headquarters in the morning was subjected to intense questioning till very late in the evening.
Kul Bhushan was not immediately available for reaction.
They said it is alleged that Kul Bhushan had acquired several 'benami' properties worth several crores from Railway contractors in lieu of favours promised to them.
Citing one such instance, the sources claimed, that a flat worth Rs 1.80 crore was allegedly purchased as 'benami property' in Bangalore as an accommodation for his son.
Kul Bhushan is also under CBI scanner for alleged corruption in a separate enquiry related to purchase of coaches for the Kolkata Metro.