Mahmoud Badi said investigations had found “misappropriation, misuse and misconduct of funds” at the Libyan Investment Authority (LIA).
The LIA has total funds worth about $70bn.
It was set up in 2006 by Saif al-Islam, one of Muammar Gaddafi’s sons.
LIA has overseas investments such as stakes in the Italian bank UniCredit, Italian football club Juventus and Pearson, the owner of the Financial Times.
Mr Badi was formerly a senior civil servant in the Gaddafi regime. He is understood to have been appointed to the LIA on an interim basis by Ali Tarhouni, who is the minister in charge of financial and oil affairs for the rebel National Transitional Council.
“We are going to dig for the truth, we need the help of expert people, we will use expert people,” said Mr Badi, speaking to the BBC at LIA’s offices in London.
“We will use all available means, we will contact all respectable institutions who were attached to these funds.
“And they have to make it up to the Libyan people, they have to bear their responsibilities.”
Earlier on Friday, the head of the Libyan Stabilisation Team at the National Transition Council said it would take at least 10 years to rebuild the country’s infrastructure.
Libya’s infrastructure was in a poor state even before the revolution due to “utter neglect”, the head of the team, Ahmed Jehani, told the BBC.