Zurich - Shares in UBS fell Tuesday, hitting a new low on the Zurich exchange, as Switzerland's largest bank said it would fight to keep client information protected.

The stock hit 9.35 Swiss francs during trading, a record low, but did recover slightly to close at 9.85, down 1.5 per cent on the day.

A US judge on Monday gave UBS until April 30 to file a response to a summons against it by authorities there, demanding that the bank hand over some 52,000 names of US clients holding assets in Switzerland. The judge scheduled a trial for July 13.

A UBS spokesman said the bank would fight the summons on the grounds that handing over the information would be a criminal offence, violating Swiss banking secrecy laws, and bilateral agreements between Washington and Berne.

There are "substantial defences allowing the bank to vigorously challenge the enforcement of the summons," UBS said.

The US tax authorities request to enforce the summons came last week, just a day after UBS admitted that its employees had conducted improper actions, and agreed to pay a fine of 780 million dollars and - under orders from the Swiss regulatory body FINMA - transfer data on clients who may have committed fraud.

Switzerland differentiates between tax evasion and tax fraud and the secrecy could only be legally violated in the latter event.

UBS would not say how many clients had their information turned over or what type of data was transferred, but reports place the number at about 250 to 300 client names.

The case against UBS has thrown into question the future of Swiss banking industry and what it might mean for the nation's economy.

In Tuesday's Geneva's Le Temps newspaper, Ivan Pictet, a senior banker, said that without the secrecy, Switzerland could see its financial sector shrink by half. Currently, the sector makes up about 12 per cent of the Alpine nation's GDP.

UBS, the largest wealth manager, has taken more hits in the financial crisis than other European banks and had to accept a bailout from the Swiss government and central bank at the end of last year.

There has been growing discord within Switzerland with the executives of the bank.

The concern for the secrecy has also affected other Swiss banks who have seen their shares decline in value as well. (dpa)