UBS isn't about to cave in a French offshore tax investigation: the Swiss bank is rejecting a billion-euro settlement with French authorities.

Zurich-based UBS is negotiating a settlement to a long-running offshore investigation in France. The matter has become a question of honor for its private bank more than a purely economical one, as CEO Sergio Ermotti said in January.

Now, Ermotti has rejected a 1.1 billion euro settlement proposed by French authorities, «Journal du Dimanche» (in French) reported on Sunday.

This means that UBS' lawyers are set to face off against French prosecutors in court this week, after negotiations between France's financial prosecutor and the bank foundered. UBS didn't comment on the report.

Human Rights Bid

The case is one of the two largest facing the bank, alongside a mortgage mis-selling probe in the U.S. which is also expected to cost billions to settle.

UBS has pulled out all the legal stops to contest the case since it was ordered to pay a 1.1 billion euro corporate bail to France three years ago. Most recently, the bank even sought help – unsuccessfully – from Europe's highest human rights court. A bid to Switzerland's highest court on grounds of data protection also failed.

Earlier this month, «Bloomberg» reported that UBS aims to pay less than 300 million euros – what it paid in Germany – to settle the probe.

The bank has promised richer shareholder payouts once its billion-dollar scandals and probes have been put aside.