MILAN (Reuters) - Italian broadcaster Mediaset (>> Mediaset SpA) said on Friday it had asked a Milan court to enforce the agreed sale of its pay-TV arm to French media company Vivendi (>> Vivendi).

Mediaset also said in a statement that it risked losing 1.5 billion euros ($1.7 billion) if Vivendi did not honour the deal struck in April.

Vivendi last month rejected the terms for its purchase of pay-TV unit Premium, saying its analysis of Premium's financial forecasts differed from those provided by Mediaset.

The broadcaster controlled by the family of former Prime Minister Silvio Berlusconi wants a judge to force Vivendi to stick to the contract and to pay damages for its late execution.

It estimates damages at 50 million euros for every month of delay starting from July 25.

"The damages sought concern purely the delay accumulated so far and possible further delays caused by inventive and dilatory proposals of different accords than the one in place," Mediaset said in a statement.

"The serious overall damage that a breaking of the contract would entail (would total) no less than 1.5 billion euros," it said.

Vivendi declined to comment.

The April deal gave Vivendi 100 percent of Mediaset Premium and handed the two companies a 3.5 percent stake in each other.

Vivendi, whose top shareholder is 64-year-old French tycoon Vincent Bollore, proposed instead to acquire only 20 percent of the loss-making pay-TV division and gradually build up a stake of about 15 percent in Mediaset.

Shares in Mediaset closed down 2 percent on Friday in line with the Milan market <.FTMIB>.

They gained 5 percent on Thursday after Italian daily Il Sole 24 Ore said Vivendi was readying a new offer for Premium with Italian merchant bank Mediobanca (>> Mediobanca Group) - of which Bollore owns 8 percent - acting as a mediator.

($1 = 0.8835 euros)

(Reporting by Valentina Za in Milan and Mathieu Rosemain in Paris; editing by David Clarke)

Stocks treated in this article : Vivendi, Mediobanca Group, Mediaset SpA