BERLIN, Germany (CNN) -- German Chancellor Angela Merkel is to meet with Otmar Hassler, the prime minister of Liechtenstein on Wednesday to discuss the growing tax-fraud investigation in Germany, The Associated Press reports.
German authorities searched Zumwinkel's home and offices in a tax evasion investigation.
German tax authorities are chasing as many as 1,000 wealthy Germans in one of the largest tax investigations in the country's history.
When Merkel meets Hassler, who is also the countries finance minister, she is expected to push the alpine municipality on greater financial transparency, AP reports.
German officials have singled out Liechtenstein foundations as a particular source for concern, and Liechtenstein says it plans to reform laws that govern this type of foundation, AP reports.
Liechtenstein's Prince Alois has in turn attacked Germany for paying an informant to obtain information on account holders with a Liechtenstein bank and has said Germany should get its own tax system under control, AP reports.
Stefan Olbermann, a spokesman for the Ministry of Finance told CNN on Tuesday that the government paid more than $6 million for a DVD that was stolen from a Liechtenstein bank and contains the names of many prominent Germans who may be involved in tax fraud scams there.
The most prominent suspect so far is former Deutsche Post Chief Executive Klaus Zumwinkel. Police raided Zumwinkel's private house and his offices at Deutsche Post last week and arrested him, though the arrest warrant was later lifted.
Zumwinkel is believed to have evaded almost $1.5 million in German taxes by investing in foundations in Liechtenstein, a tiny Alpine country between Switzerland and Austria, said Bernd Bieniossek, a spokesman for the state prosecutor.
Police and tax authorities raided private homes and banks in cities across Germany on Monday and the German government is calling on those involved to turn themselves in to the police and thus avoid a jail sentence.
When asked by CNN what kinds of people were being investigated, another spokesman for the Finance Ministry, Torsten Albig, said most were prominent and wealthy Germans.
A spokesman for Metzler, a private bank, said police raided its Frankfurt and Munich offices Monday. The spokesman said the bank has opened its banking records to the police, which it was legally obliged to do. Private banks deal with wealthy clients.
Olbermann said German authorities believe the DVD containing the names will be valid court evidence even though the German Foreign Intelligence Service bought it from a man who had stolen the data from Liechtenstein bank LGT.
Germany believes Liechtenstein, with its lax tax laws and culture of secrecy, is complicit in allowing German tax evaders to park their money in the principality.
Liechtenstein Prime Minister Otmar Hasler planned to arrive in Berlin on Tuesday for a long-planned trip to Germany and was to hold talks with German Finance Minister Peer Steinbrueck, Interior Minister Wolfgang Schaeuble, and Chancellor Angela Merkel.
Merkel planned to urge the government in Vaduz to do more to crack down on German tax evaders.
Zumwinkel resigned from his position as the CEO of Deutsche Post, one of the world's largest logistics firms, Friday. Deutsche Post announced Monday that Frank Appel, a member of the company's management board, would take over. E-mail to a friend
CNN's Diana Magnay contributed to this report.
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