Up to €5 billion ($5.7 billion) could have been disbursed to people controlling Libyan accounts, including militia groups in the country which stand accused of human rights abuses, according to a report by public broadcaster RTBF which cited an unidentified source.

RTBF said that when the UN agreed to freeze deposits held by Gaddafi's administration abroad, Belgium had done so but had not halted payments of interest and dividends.

With NATO's intervention in 2011, the UN introduced sanctions against the Libyan government's assets, effectively seizing roughly $67 billion from the Libyan Investment Authority (LIA), held across Europe and North America. In the EU, national governments froze only the original amounts, while the interest and dividends earned after 2011 remained a liquid asset.

Belgian Foreign Minister Didier Reynders told reporters on Tuesday he had not been involved in the decision to unblock interest on deposits.

"This [decision to unblock funds] is the responsibility of the Finance Ministry. I have not headed it since December 6, 2011, and have not made any decisions on this matter," Reynders said, recalling that the permission to partially unfreeze Libyan accounts was issued by the kingdom's treasury in October 2012, when the Finance Ministry was headed by Steven Vanackere.