Police searching for chemicals used to make the date-rape drug GHB raided some 600 homes and offices in Austria, Switzerland and Germany on Wednesday, German investigators said.

The raids followed months of investigation launched after police became suspicious of online orders for GBL, a chemical found in industrial cleaners, Bavarian state investigators said.

The legal chemical can be used to manufacture GHB, a potent depressant sometimes called the date-rape drug.

The GBL orders were placed to a chemical company near Munich and another in northern Germany, investigators said.

Swiss police on Wednesday searched a number of houses in 17 cantons, or states, the country's Federal Police Office said. Some of the searched premises allegedly housed laboratories for the production of synthetic drugs, the office said.

In Austria, Interior Ministry spokesman Rudolf Gollia said three houses were searched in the states of Carinthia, Lower Austria and Styria, where a possible drug lab was found.