Manchester United have lodged an official complaint with FIFA over Real Madrid's pursuit of Cristiano Ronaldo.

The 23-year-old has been the subject of intense speculation linking him with the Spanish giants despite being under contract for four more years.

Ronaldo admitted he was tempted by a move to Real but only if they can match United's £50 million-plus valuation. Madrid's president, Ramon Calderon, said the club were "honoured" that he wanted to play for them.

A United spokesman said: "On 27 May, Manchester United made clear its intention to report Real Madrid to FIFA if it continued to involve itself in the future of Cristiano Ronaldo. Unfortunately, Real Madrid has not kept its own counsel and the club feels it has no alternative but to make a formal complaint to the world governing body, which it has done today."