"Our absolute priority is the best possible solution for Switzerland. We want a U.S. settlement by year-end, but not at any price," Michael Ambuehl, the Swiss government's chief negotiator, said in an interview with Neue Zuercher Zeitung.

Ambuehl's comments on the timing contrast with those made by Switzerland's finance minister Eveline Widmer-Schlumpf last month, in which she said she expected a deal with the U.S. before elections in that country.

His comments are also a rejection of demands by some to use emergency law to hand over confidential Swiss bank data in the tax crackdown, which has been hanging over banks such as Credit Suisse (CSGN.VX) and Julius Baer (BAER.VX) for months.

Switzerland wants the investigations dropped, in exchange for payment of fines and the transfer of names of thousands of U.S. bank clients. It also wants a deal to shield the remainder of its 300 or so banks from U.S. prosecution.

In 2009, Swiss authorities reached a deal for UBS (UBSN.VX) to pay a fine of $780 million to avert criminal charges, and ultimately agreed to allow the bank to reveal details of around 4,450 clients.

Switzerland also agreed in July to do more to help other countries hunt tax dodgers following demands from the Organisation for Economic Co-operation and Development.

"We exclude the introduction of retroactive legislation to enable us to hand over bank data (that predates the U.S. deal of 2009)," Ambuehl said.

(Reporting by Martin de Sa'Pinto; Editing by Helen Massy-Beresford)

• A Permanent Economic Emergency