An investigation was launched today into the British activities of alleged multi-billion-pound fraudster Bernard Madoff.
Officials will focus on investors who lost huge sums when Madoff's financial business collapsed, the Serious Fraud Office said.
Prosecutors in the United States said a bogus business run by the former Nasdaq stock market chairman lost at least £33bn.
Investigators are approaching former employees as they work to trace those hit in Britain, the Serious Fraud Office (SFO) said.
They appealed for investors or other financiers involved with Madoff's operations in the City of London and elsewhere to come forward.
The move follows an interim report by Grant Thornton, a company brought in to liquidate Madoff's British assets.
Richard Alderman, director of the SFO, said: "This is a good example of the SFO's new, faster, approach to tackling fraud.
"The public say they want us to take early action and this is what we are doing. We will work closely with other law enforcement agencies to discover the truth behind the collapse of these huge financial structures.
"And we again ask for help from ex-employees and others."
Anyone involved with Madoff's businesses can contact the SFO online or by calling a hotline 020 7239 7272.
As the scale of the global fraud became clear, it soon emerged that several British banks were caught up in the massive scam.
The Royal Bank of Scotland - 58 per cent owned by the taxpayer - said £400m was at risk in hedge funds.
Spanish bank Santander, which owns Abbey and the savings business of Bradford & Bingley, said its potential exposure was more than £2bn.
Madoff, 70, was arrested on 11 December on securities fraud charges alleging that he duped investors out of as much as $50bn in a giant pyramid scheme.
The founder of Bernard L Madoff Investment Securities is accused of maintaining a separate and secretive investment-advising business.
Prosecutors said it served between 11 and 25 clients and had a total of about £11.4bn in assets under management.
A criminal complaint signed by the FBI said Madoff told at least three senior employees that the investment adviser business was a fraud.
It is claimed he said it had been insolvent for years, losing at least £33bn, and he was "finished".
When confronted by FBI agents at his home, Madoff told them: "There is no innocent explanation."
Madoff was released on £6.5m bail and has since been accused of attempting to post valuable jewellery and heirlooms to other family members.
Court documents revealed that Madoff had been using money from new investors to pay off old investors, a fraud known as a Ponzi scheme.
If convicted, Madoff could face up to 20 years in prison and a maximum fine of £3m.
Bernard L Madoff Investment Securities, founded in 1960, ranks among the top 1 per cent of US securities firms, according to its website.
It was one of five broker-dealers most closely involved in developing the Nasdaq stock market.Reuse content