BERLIN/ZURICH A Swiss lawmaker likened German attempts to buy data on cross-border tax evaders to bank robbery on Tuesday and the Swiss banking lobby said Berlin was acting as a receiver of stolen goods.
Switzerland's interior minister clearly sought a diplomatic solution with Berlin in a sharply escalating row with the Alpine country's most important trading partner.
"It is very important to have a good relationship between Switzerland and Germany," said Didier Burkhalter. "We now need to find a way -- and we will discuss this at Wednesday's cabinet meeting -- to ensure a stable relationship with Germany."
Germany has said it is prepared to pay for data on clients of Swiss banks who may have been evading German taxes that is being offered to authorities by a whistleblower, even if the information has been obtained illegally.
"In principle, the decision has been made," Schaeuble told the Augsburger Allgemeine newspaper, adding the legal basis was similar to a case in 2008 when Germany paid for data stolen from Liechtenstein's top bank LGT.
"Therefore we could not decide any differently," he added.
A Swiss lawmaker criticized Berlin's latest move in a simmering row over Swiss banking secrecy.
"Here we have a new form of bank robbery," Swiss lawmaker Pirmin Bischof told Germany's Deutschlandfunk radio. "Before, you had to go to the bank and get hold of the money with a weapon. Today you can do it electronically by stealing data.
"This should not be allowed in a country based on the rule of law," Bischof added.
A spokesman for the Dutch finance ministry said ministry officials had contacted German counterparts on Monday after hearing reports about the potential purchase of account data.
The spokesman said the Dutch would seek copies of whatever data Germany purchases under information-sharing agreements between the countries, with the aim of looking for Dutch account holders who may be in the data.
Switzerland has faced increasing challenges to its banking secrecy practices. Last year it agreed to relax its strict rules on client privacy to fend off potential sanctions by the G20 group of leading nations.
UBS, Switzerland's biggest wealth manager, settled with the U.S. tax authorities in August by agreeing to share data on 4,450 clients. But that deal, considered crucial to UBS's business in the U.S., is in question after a Swiss court ruled last month that most of the data cannot be released.
Shares in the two largest Swiss banks, UBS and Credit Suisse , were trading 0.3 percent and 1.9 percent higher respectively, compared to a 0.8 percent gain in the DJ Stoxx European banking sector index.
The threat of German tax authorities getting their hands on the stolen data has caused a stir among some clients of Swiss asset managers, worried their accounts could be implicated in the latest tax affair.
This comes just months after France, another key market for Swiss private banks, announced it had obtained sensitive data belonging to potential tax evaders, some of which belonged to the Swiss private banking operations of HSBC.
The SBA Swiss banking lobby urged Germany to return the data to the owner: "We expect the German government not to purchase the data and as such act as a receiver of stolen goods."
"There is no justification for resorting to illegal methods of obtaining data," it said in a statement, adding that any action against Switzerland could be counterproductive to further negotiations on issues related to bank secrecy.
German media, which estimated authorities obtained around 200 million euros in tax revenues when Germany bought the LGT data, are saying the latest whistleblower's data on 1,500 possible tax evaders could yield 100 million euros.
Authorities have estimated German citizens have 100 billion euros in Swiss bank accounts.
(Additional reporting by Lisa Jucca in Zurich, Ben Berkowitz in Amsterdam, Brian Rohan in Berlin; editing by Will Waterman and Ralph Boulton)