NAB Rawalpindi decided on Saturday to file a supplementary reference against former president Asif Ali Zardari in the money laundering case.
The statements of four approvers will be included in it.
Zardari has also been summoned on May 11 in the Joint Venture case.
Aslam Masood, the chief financial officer of the Omni Group of Companies who was arrested in October last year in London by the Interpol and brought to Pakistan, is one of the four approvers in the case.
The other three are Kiran Aman, Naureen Sultan and Adeel Shah Rashdi. They are officers of a private bank.
Former president Asif Ali Zardari, his sister Faryal Talpur and other accused are facing an inquiry into the money laundering scam involving billions laundered through fake bank accounts.
Zardari’s close aides Hussain Lawai and Anwar Majeed are also being investigated in the scandal. They both are in custody.