With Bernard Madoff today expected to plead guilty to running a $64.8 billion (£47 billion) Ponzi scheme, attention is switching to London, where he siphoned at least $250 million of investors' money into his personal accounts.

It emerged today that Madoff's sons, Mark and Andrew, became directors of the London operation Madoff Securities International Ltd (MSIL) more than 10 years ago. Both were given loans by the New York operation to buy shares in the Mayfair-based business, and each received dividends from it, according to documents filed at the time of Mark's divorce in 2000.

His stake in the London operation was valued at $5 million at the time, the Wall Street Journal reports. Bernard Madoff's wife Ruth and brother Peter were also listed as MSIL shareholders.

Although the London operation was set up in 1983, little real trading appeared to take place through it until the late 1990s when Madoff began to take an interest and expanded the operation. In November 2000, he loaned the London business $62.5 million.

Two years later, a former Madoff technology employee claims, he installed a closed-circuit TV camera to check that his British employees were not taking lengthy lunch breaks.

Madoff, 70, faces up to 150 years in jail and orders to return $170 billion.