Switzerland has pulled out of a United States Senate hearing on tax issues in protest at a civil lawsuit against the country's biggest bank, UBS, the official Swissinfo news website reported on Sunday.

The Swiss government had intended to send a representative to the US Senate hearing on Tuesday, part of a probe into alleged tax evasion by UBS clients in the United States.

The hearing will focus on the US government's request to UBS to provide more information about US citizens' accounts.

"The Swiss government regrets that the US Justice Department has threatened UBS with unilateral measures, despite the collaboration of the bank and the Swiss authorities with the American authorities," a Swiss Finance Ministry spokesman said on Sunday.

The spokesman was quoting from a letter informing the Senate of the Swiss government's decision to cancel its attendance, Swissinfo said.

The letter also stated, however, that Switzerland remained ready to collaborate with the United States "in accordance with legal arrangements and bilateral accords in place."

After months of pressure, UBS and the Swiss Financial Market Supervisory Authority (Finma) announced on Thursday the decision to hand over confidential details of 250 clients whom the US authorities suspect of tax evasion.

The UBS and Finma decision unleashed a wave of controversy in Switzerland, amid fears that it means the end of Swiss banking secrecy.

But the US government is still increasing its pressure on UBS and Switzerland.

On Thursday, the US Justice Department issued UBS with a civil lawsuit seeking the identities of about 52,000 US clients who allegedly kept billions of US dollars at the bank to evade tax. UBS has said it will fight the case.

(Xinhua News Agency February 23, 2009)