Clients of Credit Suisse may have lost up to one billion Swiss francs (£640 million) on investments connected to accused swindler Bernard Madoff.

The estimate is based on internal forecasts, reports in Switzerland said.

The bank distanced itself from any link to the scheme.

"Credit Suisse did not actively recommend or sell products invested with Bernard Madoff," spokesman Jan Vonder Muehll said.

"Furthermore, none of the funds of hedge funds offered by Credit Suisse contained holdings in Madoff funds." Prosecutors say Wall Street fund manager and former Nasdaq chairman Madoff has confessed to running a $50 billion (£34 billion) pyramid scheme fraud that ensnared investors around the world.

Meanwhile, investigators are believed to be turning their attentions to the middlemen, the so-called feeder funds, who attracted billions of investment dollars to Madoff's funds. Authorities want to know what they told their clients about how their money was being invested.

There are no allegations that these feeders knew anything about Madoff's scheme.