He would not give details on how the transaction was made or how much money was paid for the disc that contains the information but German press reports have given the figure of €2.5 million ($3.4 million).

“The CD was bought in the last couple of days and is now being held by the financial authorities of North Rhine-Westphalia” state, he said.

The data is now to be analysed and prosecutors in the state capital Düsseldorf are to decide on further steps.

The Süddeutsche Zeitung newspaper said Saturday the deal was finalised outside Germany between tax experts from the nearby city of Wuppertal and the anonymous informer who offered to sell the data.

According to several sources, it comes from the second biggest Swiss bank, Credit Suisse and should allow German tax authorities to recover up €400 million.

The federal government in early February gave the green light for North Rhine-Westphalia, home to Germany’s historic industrial heartland, the Ruhr Valley, to buy the Swiss CD. The saga prompted a high-profile debate in Germany about paying for illicit data as well as a souring of its relations with Switzerland.

German Finance Minister Wolfgang Schäuble has urged tax fraudsters to turn themselves in before they were found out. The North Rhine-Westphalian state Finance Ministry said Friday the number of people who had done so had nearly doubled within a week to 1,066.

In 2008, a similar deal netted a long list of names and bank accounts in the principality of Liechtenstein which let officials recover around €200 million in unpaid taxes and led to the arrest of the head of the logistics group Deutsche Post.

In September, Liechtenstein revealed it had since signed a deal with Germany on tax information exchange aimed at clamping down on tax cheats.