The investigation targets companies Agricover, Alfred C. Toepfer, Ameropa, Brise Agricultura, Brise Group, Bunge, Cargill, Glencore, Nidera and United Grain.
If checkups reveal these companies are guilty of price fixing, they will be fined up to 10% of their turnover.
President Traian Basescu said Wednesday five large foreign grain traders control the local grain trade market, adding that the antitrust authority should look into the matter as the difference between purchase prices is narrow, of only EUR1 for one ton of wheat.