Clients of Credit Suisse have lost up to SFr1 billion ($929 million) in the alleged fraud of Wall Street financier Bernard Madoff, according to the Swiss Sunday newspaper Sonntag.

Citing the bank's “internal estimates,” the publication said customers had lost between SFr900 million and SFr1 billion.

Credit Suisse spokesman Jan Vonder Muehll was reported confirming that clients had lost money, but he did not specify the amount. Mr Muehll added: "Credit Suisse did not actively recommend or sell Bernard Madoff investment products."

Switzerland's largest bank, UBS, said last year that the exposure of its investment bank unit to the scam was “limited and insignificant”.

Last Sunday, however, Swiss newspaper NZZ am Sonntag reported that a Luxembourg-based fund run by UBS had invested SFr1.4 billion in Madoff funds.

Mr Madoff, a 70-year-old Wall Street veteran, is alleged by US prosecutors to have confessed to having defrauded investors of $50 billion in a giant pyramid scheme that collapsed in the global financial crisis.

Meanwhile, Mr Madoff’s firm was examined at least eight times in 16 years by the US Securities and Exchange Commission and other regulators, who often came armed with suspicions, the Wall Street Journal said.

SEC officials followed up on emails from a New York hedge fund that described Bernard Madoff's business practices as "highly unusual", the paper added.