Detectives armed with search warrants searched the mansions of Mr Levett and Mr Vincent, hoping to find documents which can help explain how Sumitomo's losses could have happened.
Both men are believed to have been in Monte Carlo, at their second homes in the principality, where they moved for tax reasons earlier this year, at the time of the raid on Wednesday.
The search was co-ordinated by the Serious Fraud Office, which has been investigating the copper trading losses incurred over a 10-year period by Sumitomo trader Yasuo Hamanaka.
Mr Vincent, who is known as "Copperfingers", owns a large manor in West Tytherley, near Salisbury. Mr Levett's house is at Alresford, Hampshire.
Both men and their company, Winchester Commodities, were at the centre of a long investigation by the Securities and Futures Authority.
The SFA was reacting to allegations of fraud made after the Chilean state copper trading company suffered enormous losses on the market in 1993.
Since Sumitomo admitted its losses in June, investigators have been eager to establish whether there is a UK connection.
Both Mr Levett and Mr Vincent have strongly denied they were implicated in the losses, saying that the SFA investigation, concluded in March had given them a clean bill of health.Reuse content