The investment-banking arm of Credit Suisse has become the latest target of claims from the Italian dairy company Parmalat.
It is seeking damages of €7.1 billion (SFr11 billion) from Credit Suisse First Boston (CSFB), which has described the claims as "unfounded".
Details of the action were contained in Italian newspapers on Tuesday. They outline the legal battle by Parmalat administrators against firms they say helped provoke the dairy giant's collapse.
Parmalat, which went insolvent at the end of 2003 amid a crippling financial scandal, is due to return to the stock market on Thursday after creditors approved a €12 billion debt-for-equity swap.
The company had already sued CSFB in August last year, filing a claim for €248.3 million over a convertible bond it underwrote.
A CSFB statement said the bank was aware of the new claim brought by Parmalat's extraordinary administrator.
The allegations are without foundation, said CSFB, and added that it would be vigorously contesting the claim.
On Friday, another Swiss bank - the Graubünden Cantonal Bank - said it had appealed against injunctions for it to pay damages of about SFr60 billion related to Parmalat's collapse.
The bank issued a statement saying the sum demanded lacked any rationality or base and could not be substantiated in any way.
It had earlier said that it expected to see criminal investigations in the wake of the Parmalat scandal, adding it had always worked closely together with the authorities.
The bank said its relation to Parmalat was already fully researched and documented by consultants at PriceWaterhouseCoopers which found no fault in the bank's business relationship with the company.
The bank said the Swiss Federal Banking Commission had also given it a clean sheet.
In August Switzerland's largest bank UBS said it would defend itself against claims from Parmalat, which is seeking to recover money related to bond sales.
Parmalat is seeking €290 million plus interest in the action against UBS, filed in a Parma court, and reserves the right to bring another suit to recover damages.
"We believe that the transaction in question was entirely valid and therefore any attempt to declare the transaction invalid will be met by a vigorous defence by UBS," the bank said in a statement.
Meanwhile, the Federal Prosecutor's Office has confirmed that a man suspected of money laundering has been held in detention since mid-September but refused to give further details.
Reports say the suspect is a former employee of the Graubünden Cantonal Bank.
swissinfo with agencies
Credit Suisse First Boston, UBS and Graubünden Cantonal Bank have all said that action against them resulting from the collapse of Parmalat is unfounded.
Parmalat was Europe's biggest dairy company when it was declared bankrupt at the end of 2003.
Its worldwide operations included nearly 140 production centres, with a staff of 36,000.