The Financial Times Deutschland said two compact discs of data, including one on accounts at top Swiss bank UBS, were obtained while the Sueddeutsche Zeitung reported four disks were purchased.
The Sueddeutsche Zeitung cited an expert involved as saying the "extremely interesting" disks contained data on Germans trying to evade taxes at home
with the help of Swiss banks.
Another source told the Financial Times Deutschland that the stolen data from UBS was significant as it contained names as well updated advice on how
to evade German taxes through the use of foundations.
In addition it also acquired UBS training documents that show how it was active in aiding clients avoid paying taxes, it said.
North Rhine-Westphalia Finance Minister Norbert Walter-Borjahns declined to confirm any specific purchases to the newspapers, but said they regularly
receive offers of stolen Swiss bank data.
The region has previously bought stolen data, incurring the anger of the German federal and Swiss authorities, which want to ban the practice under a
new treaty that is still in the process of being ratified.
In 2010, German tax authorities recuperated 1.6 billion euros from tax dodgers after buying data on Germans with assets in Switzerland and
Liechtenstein, according to the press.
Switzerland reacted angrily last March by issuing arrest warrants for three German tax inspectors on charges of economic espionage for purchasing a stolen
CD naming German customers of Credit Suisse, Switzerland's second biggest bank.