Italy’s communications regulator Agcom has ordered Vincent Bolloré’s French media group Vivendi to cut its stake in either Mediaset or Telecom Italia, ruling that building large stakes in both companies violates the country’s antitrust laws.

At present, Vivendi is the biggest single shareholder in Italy’s main telecoms firm Telecom Italia, with a 24% stake, and recently built up a 28.8% stake in Italy’s biggest private broadcaster Mediaset.

The ruling, which was issued on Tuesday, said that Vivendi must get rid of its stake in one of the companies within a year and Agcom ordered the company to present a detailed plan as to how it would comply within the next 60 days. The regulator said the ties between the three companies risked causing a negative effect “on the existing level of competition in the markets involved and on the degree of pluralism in the media system.”

Vivendi released a statement on Tuesday saying that it “neither controls nor exercises a dominant influence on Mediaset” and said it was considering legal action.

“Vivendi reserves the right to take any appropriate legal action to prevent its interests, including filing an appeal to the Agcom decision at the Regional Administrative Court and to submit a formal complaint to the European Commission for the breach of EU law,” it read.

Mediaset, meanwhile, praised the ruling in a brief statement issued on Tuesday evening.

The move is sure to come as a blow to Bolloré, who has made no secret of his ongoing strategy to expand into southern Europe to create a non-U.S.-based global media giant. The company currently owns Canal Plus, Studiocanal and Universal Music Group and is a key shareholder of Italian investment bank Mediobanca. Vivendi has been attempting to tighten its grip on Telecom Italia and also began aggressively building its stake in Mediaset in December, when it only had a 3% stake in the company.

It marks the latest chapter in a long-running public battle between Mediaset and Vivendi, which has been at locked horns since July 2016 when Vivendi backed out of an agreement that would have given Vivendi control of Mediaset’s pay-TV unit, Premium, and given the two companies 3.5% equity stakes in each other.