The withdrawn $250 million was released to the Office of National Security Adviser (ONSA) without appropriation.
According to a report by The Nation, EFCC chairman, Ibrahim Magu, approved the letter of invitation which has been sent to the former minister who served two terms under former presidents, Olusegun Obasanjo and Goodluck Jonathan.
The invitation was based on a recommendation by detectives investigating the whereabouts of the $500 million loot as the withdrawn $250 million was released to the Office of National Security Adviser (ONSA) without appropriation.
The Nation's report also noted that about $36,155,000 (N13,015,800 billion) out of the $250million was also withdrawn in cash "without any purpose" on March 2nd, 9th, 16th and 18th of 2015.
A source said, "Following preliminary findings, a strong recommendation was made to the Acting EFCC chairman for an interactive session with Dr. Ngozi Okonjo-Iweala.
"Magu has approved the invitation of the ex-minister. We have dispatched a letter of invitation to her. We are hopeful that she will respond.
"Her presence is necessary because there were issues about the $250million released especially why $36,155,000 (N13,015,800billion) was withdrawn in cash.
"She needs to assist the EFCC team on what became of the balance of $250million which was yet to be traced.
"She has to explain why some of the funds were diverted to extraneous matters including media services, opinion polls and personal matters."
Dr Okonjo-Iweala had signed a memo to then-president, Jonathan, requesting the release of $300m from the Abacha loot to former National Security Adviser, Sambo Dasuki, after his office requested the sum in a memo sent to the former Coordinating Minister for the Economy on January 12, 2015.
In the memo, she stated that the fund will be used by ONSA to purchase ammunition, security and other intelligence equipment for security agencies in order to enable them confront the ongoing threat of terrorist group, Boko Haram.
The memo read, "This request is sequel to the meeting you chaired with the committee on use of recovered funds where decision was made that recovered Abacha funds would be split 50-50 between urgent security needs to confront Boko Haram and development needs (including a portion for the Future Generations window of Sovereign Wealth Fund).
"This letter is to seek your approval to borrow these funds, for now, to disburse to the NSA. These funds form part of projected FG Independent Revenue to be appropriated.
"In light of this and for accountability, given the peculiar nature of security and intelligence transactions, we would expect the NSA to account to your Excellency for the utilization of the funds."
Then-president Jonathan approved the request on January 29, 2015, with only $250million released to ONSA.