A media report said that major Western pharmaceutical companies carried out tests of medications in the 1980s on patients in communist East Germany, in some cases without the subjects' knowledge.
"We have documents showing there were contracts between Western drug companies and East German institutions for medical tests," a staff member at the German national archive told AFP, partially confirming a report in the daily Der Tagesspiegel.
The newspaper, which examined the documents, reported that more than 50 Western firms had contracts with East Germany's Health Ministry to carry out a total of 165 medical tests between 1983 and 1989.
In exchange, the communist authorities were paid up to 860,000 deutschmarks (around 430,000 euros today or $567,000), according to the report, at a time when East Germany was desperate for hard currency.
Der Tagesspiegel said the companies involved included Bayer, Schering, Hoechst (now Sanofi), Boehringer Ingelheim and Goedecke (today owned by Pfizer).
It said the test subjects often were not informed, citing seven specific cases in which patients said later they had been unaware they were involved in testing. The national archive said it could not confirm this.
Regional public broadcaster MDR, which also reported on the issue, cited the case of a 60-year-old patient, Gerhard Lehrer, who was recovering from a heart attack in a Dresden hospital in 1989.
After receiving "special" medications "that were not on the market" prescribed by a doctor at the clinic, his condition deteriorated further.
Lehrer's wife secretly pocketed some of the pills. When MDR had them tested at her request, it learned they were placebos that it said were part of a study commissioned by Hoechst.
Swedish furniture giant Ikea admitted in November that some of its suppliers used forced labour in communist East Germany and expressed "deep regret" that its controls were less strict at the time.
According to media reports, mail-order companies Neckermann and Quelle also employed East German prisoners against their will.