Manchester United have lodged an official complaint to Fifa about Real Madrid’s pursuit of Cristiano Ronaldo.

The Premier League champions are angry that the Spanish club have repeatedly and publicly courted the Portugal forward without lodging an official bid for him, calling their tactics “totally unacceptable”.

United confirmed their decision in an official statement today, which read: "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. The precise content and nature will remain confidential."

Fifa confirmed they had received the complaint. "We have received an official request from Manchester United to look into the matter," a spokesman said. "We have only just received the documents so we need some time to analyse them before we can make any decision."

Bernd Schuster, the Real Madrid coach, is on record as saying that Ronaldo, who was named Player of the Year by both the Professional Footballers’ Association and the Football Writers’ Association.

“There are other players we have been looking at but everything has slowed down a little due to all this Cristiano Ronaldo business, seeing as he is the big priority for the club," Schuster said.

“The English way has been a perfect education for a player with such exceptional individual talent. There he has learned to enjoy his football as a complete professional. This means we would get a Cristiano who would arrive here with his lessons learned.”

Ronaldo has continued to send out mixed messages about his future after helping United win the Champions League and retain their Barclays Premier League title.

He recently told Brazilian website Terra: “I would like to play for Real Madrid - but only if it is true they are ready to pay what Manchester United ask of them. However, it does not depend on me.”

The Portugal international then vowed not to discuss the subject further until after Euro 2008 in Austria and Switzerland, where he is representing his country.

United’s action is bound to dismay Real as only last week, president Ramon Calderon insisted his club would never risk their relationship with them by trying to unsettle Ronaldo.

“We can’t do anything if the club that owns him don’t want to sell,” he told Marca. “We would never (approach a player under contract) as this is not the policy of Real Madrid, and especially not with a club who we are such good friends with.”