The European Commission says it is investigating a number of cement companies, including Switzerland's Holcim, on suspicion of illegal cartel activity.
Officials from Brussels raided several major companies' offices including market leader Lafarge of France, Holcim – the second largest player – and Mexico's Cemex.
Other firms included Germany's Dyckerhoff and HeidelbergCement.
The Commission has reason to believe that the companies concerned may have violated EC Treaty antitrust rules that prohibit cartels and restrictive business practices and/or abuse a dominant market position, a statement said on Wednesday.
In 1994 the Commission fined cement companies, including Holcim, for operating a cartel, dividing up cement markets and sharing information.
"At this stage it is hard to tell what the impact will be," commented Zurich Cantonal Bank analyst Martin Hüsler. "In the worst case, the probe could be pretty bad. Punishment can be up to ten per cent of annual turnover."
"When something like this happens it will not help cement companies to increase prices in the next couple of months," he added.
A Holcim spokesman confirmed that antitrust authorities had searched group offices in France, Belgium, Germany and Britain, adding that the company was cooperating fully.
Shares at Holcim have slipped by almost 50 per cent over the past year.