Italy's antitrust authority has opened a probe into four cement makers for alleged price fixing, it said in a statement on Thursday.

The companies under investigation include Buzzi Unicem, Cementir Italia, Industria Cementi Giovanni Rossi and Holcim Italia, the watchdog said.

The authority said it had carried out inspections in the offices of the four firms on 25-26 November.

"The case concerns the possibility of an agreement ... to coordinate cement sales price increases," it added.

Buzzi Unicem today issued a press release stating that it is "confident of being able to demonstrate during the investigation the absence of any non-compliant conduct."