The sources said questioning revolved around accounts of IDS Tunisia and remittances received by it.
They said some documents which Khaitan was not carrying on Friday were brought by him.
The CBI claimed that Khaitan was being evasive during questioning and ‘concealing’ information.
The agency sources said managing director of IDS Infotech Partap K Aggarwal and chief executive officer of Aeromatrix Info Solutions Pvt Ltd Praveen Bakshi have been called in connection with its probe in the case.
It is believed that their firms were used to route alleged bribe money in India.
Former Air Force chief S P Tyagi has also been called on Monday again for a fresh round of questioning.
The sources said Aggarwal, Bakshi and Tyagi have been called after some new facts have emerged during the questioning of the four accused on Saturday.
Sanjeev Tyagi has not denied his relations with European middlemen Guido Haschke and Carlo Gerosa saying that they know him five to six years before the order was placed.
He has said that the payments received by him were for power sector jobs which were all received through proper banking channels with income tax paid on them. He has said that payments received from middlemen were not for helicopter deal but for some power sector job.
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