Christian Schmidt-Sommerfeld, Munich's chief prosecutor, said the raids were done in cooperation with investigators in Bochum who are looking into more claims of tax evasion, following the resignation of Klaus Zumwinkel, chief executive of Deutsche Post. Bochum prosecutors last week said Zumwinkel is suspected of evading about 1 million euros ($1.5 million) in taxes by transferring money to tax haven Liechtenstein.

German Chancellor Angela Merkel made clear Monday that she will press Liechtenstein for greater transparency, arguing that the tiny country's reputation is at stake.

So far, no other people suspected in the investigation have been named, but the government acknowledged over the weekend that its Federal Intelligence Service, or BND, had paid an informant some euro5 million ($7.3 million) for a list with the names of account holders from a Liechtenstein bank.

"The government received an unsolicited offer of information," Ulrich Wilhelm, Chancellor Angela Merkel's spokesman told reporters Monday.