According to the magazine, doctors received household goods in exchange for putting patients onto drug monitoring studies for the drug company Trommsdorff.

A form in the studies invited doctors to tick boxes next to which reward they would like to receive – for 5 patients they could get a flat-screen TV or an iPod, for 7 patients a DVD recorder, for 12 patients a coffee machine, for 14 patients a satellite navigation system, and for 18 patients they could choose between a laptop, a digital projector, and a desktop computer with printer.

Drug monitoring studies are ostensibly designed to observe the side effects of medication, but are treated with suspicion because many believe their main purpose is to boost sales.

Trommsdorff declined to tell Der Spiegel how many doctors had received the gifts, but assured the magazine that they were “fully cooperating” with the state prosecutors.

Up until now, the investigation has centred on managers and sales representatives of Trommsdorff. The move to investigate 480 doctors across the country marks a significant widening of the operation.

“I can’t rule out that this number won’t increase significantly,” senior public prosecutor Robert Deller told Der Spiegel.