* Mediaset says Vivendi now only wants 20 pct of pay TV

* Mediaset says French aims for 15 pct stake

* Vivendi CEO says no plan to take control of Mediaset

(Recasts, adds comments by Fininvest, De Puyfontaine, analysts, shares and Mediaset growth figures)

By Giulia Segreti and Agnieszka Flak

MILAN, July 26 (Reuters) - Vivendi VIV.PA has backed away from a deal to buy the pay-TV business of Mediaset MS.MI in an unexpected move the Italian broadcaster's biggest shareholder said could mean that a full takeover was on the agenda.

Mediaset, controlled by the family of former Italian Prime Minister Silvio Berlusconi, said on Tuesday Vivendi had proposed an alternative agreement that would give it a bigger direct stake in the broadcaster than originally agreed.

Mediaset said Vivendi wanted just 20 percent of its pay-TV division Mediaset Premium and not 100 percent as agreed in April. The French group also now wants to take around 15 percent of parent Mediaset in the next three years via a convertible bond.

Fininvest, the Berlusconi holding company that owns 35 percent of Mediaset, said Vivendi's decision to rejig the terms of the deal showed the French group's agenda was to build a significant stake in Italy's biggest private broadcaster.

Vivendi, headed by media tycoon Vincent Bollore, is trying to build a European media and content group which will also have partnerships in the telecoms sector. It has already built up a stake of 24.7 percent in Telecom Italia TLIT.MI .

Bollore, a friend of former prime minister Berlusconi, has longstanding connections in Italy and is a shareholder in Mediobanca MDBI.MI , the investment bank that has for years been central to deal making in Italy.

Vivendi Chief Executive Arnaud de Puyfontaine said the group did not plan to take control of Mediaset and said its strategy had not changed.

"The strategy is the same, what changes is the way we make it happen because we have a different perspective on some aspects of the business," de Puyfontaine said, speaking to reporters in Milan.

Vivendi's unexpected change of tack hit Mediaset shares, which were down 8.3 percent by 1142 GMT.

"The move by Vivendi wants to put the Berlusconi family in the corner, and force them to give up the control of Mediaset, at a time when Berlusconi is selling off several assets of his empire," one Milan-based media analyst said.

"This new move by Vivendi would signal a stronger appetite for Mediaset," Banca Akros analyst Andrea De Vita said.

Disagreements over the deal arose last Thursday when Mediaset Chief Executive Pier Silvio Berlusconi, who is Berlusconi's son, met Vivendi chairman Bollore, a source familiar with the matter told Reuters.

Bollore asked for a discount on the price of the deal as he believed Mediaset Premium was not worth the original value stipulated in the deal, the source said.

The share-based deal had valued Mediaset Premium at 800 million euros ($912 million), with the two companies taking a 3.5 percent stake in each other. urn:newsml:reuters.com:*:nL5N17B1QC

At the beginning of July, Pier Silvio Berlusconi said financial results of the pay-TV unit were in line with the business plan. urn:newsml:reuters.com:*:nI6N19M00Z

He said Mediaset's advertising revenues in the first six months of the year would be up almost 4 percent, and would rise 2 percent at the end of 2016.

<^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ BREAKINGVIEWS-Vivendi has upper hand in Italian cable tangle ID:nL4N1AC2UL

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^> (Additional reporting by Valentina Za and Giancarlo Navach in Milan and Mathieu Rosemain and Gwenaelle Barzic in Paris,; writing by Stephen Jewkes, editing by Louise Heavens and Jane Merriman) ((Giulia.Segreti@tr.com; +39.02.66129416; Reuters Messaging: giulia.segreti.thomsonreuters.com@reuters.net))

Keywords: MEDIASET VIVENDI/PAYTV