The key shareholder in Mediaset says it had asked a Milan court to order France's Vivendi to comply with the contract to buy the Italian broadcaster's pay-TV unit.

Fininvest, the holding company of former Prime Minister Silvio Berlusconi, wants Vivendi to pay €570 million in damages for wanting to change the terms of a deal that gave it full control of Mediaset's pay-TV Premium and handed the two companies a 3.5 per cent stake in each other.

Fininvest said in a statement the economic damage stemmed from a fall in value of Mediaset shares - which are down almost 15 per cent since Vivendi's change of heart - and harm to the group's corporate image.

The move comes after Mediaset on Friday asked a court to enforce the sale and order Vivendi to pay €50 million for every month of delay in the deal, adding that if it fell through it would incur in damages for at least €1.5 billion.