Western financial institutions were some of the biggest holders of funds for the Libyan Investment Authority, the sovereign wealth fund controlled by the regime of Muammar Qaddafi, it is claimed.
Leaked documents obtained by Global Witness, an advocacy group based in the UK, purport to show where the Libyan government's oil revenues were invested.
"The Libyan people could not know where it was invested or how much it was, because banks have no obligation to disclose state assets they hold," said the group, which focuses on human rights issues and environmental exploitation.
"It is essential for banking regulators to investigate whether these banks have done enough to ensure that state funds have not been diverted to the Qaddafi family's personal benefit."
According to the documents, the total assets of the Libyan Investment Authority (LIA) stood at US$53.3bn (Dh195.78bn) as of June 30 last year.
The fund held $292.6m in cash deposits with HSBC, and a further $281.2m in structured product investments. Cash worth $43.6m was held with Goldman Sachs, while the fund also allocated $151.7m to Goldman's private-equity funds. The LIA invested in funds at a number of other banking giants, including Royal Bank of Scotland, JPMorgan, Nomura and Deutsche Bank, the papers show.
Many of the fund's investments turned out poorly. The French bank Societe Generale took $1.8bn from the fund for structured product investments, which had halved in value by the time of the documents' release. A $300m structured investment with Lehman Brothers, the collapsed investment bank, had been written off.
The bulk of the deposits were held by the central bank of Libya, although its subsidiary Arab Banking Corporation (ABC) also held $406.38m of deposits. ABC is not subject to the UN's freeze on Libyan assets.
The fund also held $5.4m in Abu Dhabi Government bonds.
HSBC, Royal Bank of Scotland and Goldman Sachs did not comment.
The UAE Central Bank is complying with the UN sanctions on Libya, but the regulator declined to comment on whether banks and other financial institutions in the Emirates had been used as a conduit for Libyan funds.
HSBC Middle East runs a representative office in Tripoli, which has continued to operate despite civil war in the country, the bank said this week.