According to Premium Times, the funds were transferred from the loot recovered from late military ruler, Sani Abacha.
Okonjo-Iweala was said to have turned blind eyes to how the money was spent but, according to a document sighted by the online news portal, she requested that former President Goodluck Jonathan directly demand accountability from Dasuki.
Report said Abacha stole an estimated $5 billion from Nigeria, the funds which are being returned to the country's coffers in portions following agreements with Switzerland and the United States.
About $700 million is believed to have been returned from Switzerland alone - the total amount of funds returned is however unclear.
Dasuki is being investigated for his role in the disbursement of $2.1 billion and N643 billion meant for the procurement of arms to fight the raging insurgency in Nigeria’s north east region.
Also facing probe are former governor of Sokoto State, Attahiru Bafarawa, and founder of DAAR communications, owners of Africa Independent Television and Raypower radio network, Raymond Dokpesi.
According to a letter dated January 20, 2015 and addressed to Jonathan, the money was transferred following a January 12, 2015 request by the office of the NSA under Dasuki for funds for the procurement of arms and ammunition as well as intelligence equipment.
The letter, reportedly seen by Premium Times, also showed that 50 per cent of the recently recovered Abacha loot was allotted for “urgent security need” such as the procurement of arms and ammunition while the other half was set aside to be used for development purposes.
Okojo-Iweala allegedly wrote in the letter, “Please find a request by the National Security Adviser (NSA) for the transfer of $300 million and £5.5 million of the recovered Abacha funds to an ONSA [Office of the National Security Adviser] operations account.
“The NSA has explained that this is to enable the purchase of ammunition, security, and other intelligence equipment for the security agencies in order to enable them fully confront the ongoing Boko Haram threat.
“His request is sequel to the meeting you chaired with the committee on the use of recovered funds where the decision was made that recovered Abacha funds would be split 50-50 between urgent security needs to confront Boko Haram and development need (including a portion for the Future Generations window of the Sovereign Wealth Fund)."
She further said the letter was to seek Jonathan’s approval for the funds to be disbursed to the ONSA and noted that she expected Dasuki to directly give an account of how he spent the funds to the ex-president.
“This letter is to seek your approval to borrow these funds, for now, to disburse to the NSA. These funds form part of the projected Federal Government Independent Revenue, to be appropriated, in the light and for accountability, given the peculiar nature of security and intelligence transactions, we would expect the NSA to account to Your Excellency for the utilisation of the funds,” she added.
The document showed that Jonathan approved the transfer on January 30, 2015.