BONN, Germany — German authorities raided nine mattress companies Thursday as part of a nationwide investigation into price fixing, the Deutsche Welle website reported.

Officials with the Federal Cartel Office said the manufacturers were suspected of offering retailers advantages, or threatening them with disadvantages, to make them stick to a minimum price on certain mattresses.

According to the financial daily Handelsblatt, the German mattress industry was in turmoil over the raids. Companies including Malie, Tempur, Fey & Co. and Schlaraffia confirmed their premises had been searched, Deutsche Welle said.

If found guilty of price fixing, the companies face heavy fines, the report said.