Vivendi’s Paris headquarters were raided by police Thursday as part of an investigation into alleged market manipulation involving its acquisition of a stake in Italian broadcaster Mediaset.

The probe was launched by Milan prosecutors following a criminal complaint filed by Mediaset and its majority shareholder Fininvest, a holding owned by former Italian Prime Minister Silvio Berlusconi and his family, in December.

The Paris headquarters of the French bank Natixis, one of the banks mandated by Vivendi to carry out the acquisition of Mediaset’s stake, has also been searched, according to local reports. Contacted by Variety, Natixis was unavailable to comment.

Vivendi confirmed the raid and issued a brief statement saying that its management “reaffirms that it acquired its stake in Mediaset totally legally and transparently and remains absolutely confident in the conclusion of this disagreement.”

Vivendi is currently Mediaset’s second-biggest shareholder with a 28.8% stake and 29.9% of voting rights – behind Fininvest, which has a 39.5% stake and 41.1% of voting rights.

Vivendi and Mediaset’s legal spat goes back to July 2016, when Vivendi backed out of its agreement to acquire a majority stake in Mediaset’s pay-TV unit. Mediaset and Fininvest each filed a civil complaint and are seeking an estimated 2 billion euros (for Mediaset) and 1 billion euros (for Fininvest) in damages in the case. These complaints are now in mediation.