Mediaset and Vivendi have been at odds since 2016 when the French conglomerate pulled out of an 800 million euro ($964.08 million) agreement to buy Mediaset's loss-making pay-TV unit.

Here is a timeline tracing the dispute.

** April 2016

Vivendi agrees to buy Mediaset's Premium pay-TV business, billed as a major step in billionaire businessman Vincent Bollore's plan to build a southern European content and video-on-demand powerhouse. The two companies agree to take a 3.5% stake in each other as part of the deal.

** July 2016

Vivendi backs away from the original deal, proposing an alternative that would give it a bigger direct stake in the broadcaster than initially agreed.

Vivendi says the main reason for the change is the unreliability of Mediaset Premium's annual financial forecasts over the 2016-2018 period.

The deal falls apart as Mediaset rejects the new proposal by Vivendi and announces legal action against the French group.

** Dec. 2016

Vivendi builds up a 28.8% stake in Mediaset over the month in a move condemned by the Italian broadcaster.

** April 2017

Italy's communication regulator orders Vivendi, which is also the top shareholder in Telecom Italia, to cut its stake in either the telecoms group or Mediaset within a year to comply with rules designed to prevent a concentration of power.

** April 2018

Vivendi transfers 19.19% of its shareholding in Mediaset to a trust to comply with the April 2017 ruling by the Italian communications regulator.

** Sept. 2019

Mediaset shareholders back a plan, unveiled in June, to create a pan-European media group under a new Dutch holding, fending off opposition from Vivendi.

Under the plan, both Mediaset and its Spanish unit will be merged into a Dutch company dubbed MediaForEurope (MFE).

Vivendi, which says the new structure tightens the grip of Fininvest on the group, challenges the plan in court in Spain, in Italy and in the Netherlands.

** June 2020

Mediaset increases its overall potential stake in German broadcaster ProSieben to 24.2% as it presses ahead with its own plans to create a pan-European TV champion.

** Aug. 2020

Mediaset says it is withdrawing plans to restructure under a Dutch holding company but adds its strategy remained valid and it would seek alternatives.

Vivendi asks to meet top executives at Mediaset to discuss a deal to end its long-running row. Mediaset said any potential deal would have to include compensation.

** Sept. 2020

The EU's Court of Justice rules that the Italian law that forced Vivendi to forfeit two thirds of its stake in Mediaset violates the bloc's rules, virtually handing back voting rights for its full 29% stake in Mediaset.

** Nov. 2020

Italy approves legislation requiring communications watchdog AGCOM to start a probe into Vivendi's twin stakes in Mediaset and TIM. The investigation could trigger other restrictions on the French group's interests in the country.

Vivendi lodges a complaint with the European Commission.

** Dec. 2020

Italian prosecutors conclude a probe into Vivendi's Vincent Bollore and Arnaud De Puyfontaine for alleged market manipulation and obstruction of regulators in a case involving the French group's stake building in Mediaset

** Jan. 2021

Mediaset and Vivendi are among potential rival bidders in the race for the controlling stake in French broadcast group M6 sources close to the matter told Reuters.

($1 = 0.8298 euros)

(Reporting by Elvira Pollina)