Vivendi Universal has been approached with a Euros 15bn offer for its entertainment assets by a consortium of businessmen - including oil billionaire Marvin Davis (pictured), the former owner of Twentieth Century Fox - but is refusing to sell. As a result, Vivendi shares ended the day (Thursday) up 21.2% in Paris at Euros 13.8 - the largest single-day rise for the company in years.

According to The Wall Street Journal the offer was for assets including Universal Studios, Universal Music as well as Vivendi's cable networks and theme park interests. The Journal said that Davis had pulled together a group of private-equity firms and that it had held some preliminary discussions in Paris last week with Vivendi Universal.

A Vivendi source told Reuters: "It is true that there was an approach, but these assets are not up for sale. The proposal did not interest the company."

However, the Euros 15bn bid - which additionally included the assumption of Euros 5bn of debt - could represent a possible alternative for Vivendi Universal as it weighs the fate of its entertainment assets. It is widely believed that the most common scenario is for Vivendi to put its entertainment holdings into a separate publicly traded company to be headed by Barry Diller. VU's chief Jean-Rene Fourtou announced in September than he was planning to spin off Vivendi Universal Entertainment, now headed by Diller, in order to float it on the NYSE.

In a bid to reduce its Euros 19bn debt and drag itself out a 'junk' rating, the media and entertainment giant is currently fast shedding assets (some Euros 5bn to date). Vivendi Universal recently raised Euros 1bn by placing bonds to institutional investors and is closing in on the sale of 50% of its 40% stake in water utility company Vivendi Environnement for some Euro 1.8bn .

At the same time the group is seeking to raise funds in order to be in a position to pre-empt British telecom giant Vodaphone's Euros 4bn bid for the 26% stake held by British Telecom in cash-rich French telecoms company Cegetel.

Davis, 77, bought Twentieth Century Fox in 1981 for $724m, but in the early 80s the studio languished, producing few blockbusters. In the mid-1980s he hired Paramount Pictures movie chief Diller to run Fox. According to the Journal, the two strong willed executives clashed over a variety of issues. With Fox needing cash, Davis found a new partner in the form of Rupert Murdoch - who paid $250m for a 50% stake in Fox in 1985, increasing this to full ownership later.