Angolan officials transferred $618m to the Sberinvest account in Cyprus, believing they were paying the Russians.

Angolan officials blame inefficient farming, poor roads and the devastation of a 27-year civil war for the distortions.

As Feinstein explained, it had been much easier to trace the Angolan officials who benefited from the criminal transaction.

The moves at Quantum Global came after Angolan officials visited Mauritius last week, a regulatory source on Mauritius told Reuters.

Many of them were refugees from Angola's 27-year civil war, who, Angolan officials said, had lived in Congo legally for decades.

Senator Carl Levin said he planned to refer HSBC to its U.S. bank regulator in connection with questionable accounts it provided for senior Angolan officials.