Switzerland rejects U.S. demands that the country's largest bank UBS should hand over the data of 52,000 U.S. clients, Swiss newspaper Berner Zeitung quoted the Swiss justice minister as saying on Saturday.

These are UBS's client data, she said. They are requested without substantiated suspicion. This is against our legal norms and it is against the agreements we have with the United States.

One can absolutely not cave in to this demand, she was quoted as saying.

Swiss banks are forbidden by law to divulge information on clients unless it is suspected that a Swiss criminal law has been broken. Under Swiss law, tax fraud is a criminal offence, but tax evasion is not, although it can result in fines.

Switzerland has come under fire after allowing UBS to disclose the identity of about 300 of its U.S. clients to avert criminal charges that Swiss regulators said would have put its existence at risk and hurt the economy.

A day after the agreement, U.S. tax authorities said they were still pursuing a civil lawsuit against UBS, seeking to access the data of another 52,000 Americans it says are hiding about $14.8 billion in assets in Swiss bank accounts.

On Friday, Swiss government said it resolutely rejected criticism of Switzerland's laws, but it would improve cooperation with other countries about tax offences and the taxation of savings income.

(Reporting by Sven Egenter, editing by Mike Peacock)