Berlin tax authorities are preparing to raid the homes of hundreds of wealthy Germans after uncovering a €4 billion tax evasion scam in a Liechtenstein bank, writes Derek Scally, in Berlin

The scam claimed its first prominent victim yesterday when Deutsche Post chief executive Klaus Zumwinkel offered to resign.

He has admitted hiding €1 million from the German tax authorities.

The departure of Mr Zumwinkel, one of Germany's most influential executives, caused shockwaves in the worlds of German business and politics yesterday, with the promise of further well-known faces to follow.

"The government has accepted his offer to resign. I consider it unavoidable after what happened," said the chancellor Angela Merkel yesterday. "Like many people in Germany, this is beyond anything I could have imagined."

Deutsche Post went public eight years ago but Berlin remains the largest investor of the firm, owner of parcel firm DHL.

News of Mr Zumwinkel's resignation came a day after tax officials raided his Cologne villa and Bonn office. After he was released on bail, Deutsche Post insisted their chief executive was staying on.

He showed up for work as usual at 7am yesterday. But after a wave of outrage from Berlin reached Bonn by midday, a Deutsche Post spokesman announced Mr Zumwinkel's offer to resign, after 19 years as chief executive, "to prevent further damage to the company".

Deutsche Post logistics chief Frank Appel is expected to be named new company chief on Monday.

German tax authorities say they have launched 125 separate tax fraud investigations and that nearly 1,000 people can expect a visit from investigators. "It's clear that people with larger incomes have lost the run of themselves," said Social Democrat (SPD) leader Kurt Beck yesterday.

After a recent return to the left, his party is expected to earn the greatest political capital from the tax evasion revelations, the latest in a long string of scandals to hit German managers. SPD federal finance minister Peer Steinbrück attacked yesterday a "consulting industry that points out ways to get around the German taxman".

"Events like this leave people outraged," he said.

The investigation has drawn attention to the principality of Liechtenstein, a popular tax refuge with 35,000 citizens, 80,000 letterbox firms and - measured on per capita gross domestic product - an average income twice that of neighbouring Switzerland.

At the centre of the German tax evasion scandal is the Liechtenstein Global Trust (LGT) bank, owned by Hans-Adam II, Prince of Lichtenstein.

Yesterday the bank, which manages assets worth €62 billion, issued a statement noting its suspicions that bank account details stolen six years ago had been "illegally forwarded".

"Customers who may be affected by the stolen data will be contacted personally by the bank," the statement said.