Manchester United took the extraordinary step yesterday of reporting Real Madrid to Fifa, world football’s governing body, over their public pursuit of Cristiano Ronaldo. Relations between two of the world’s biggest clubs seem certain to deteriorate further in the coming weeks. Real are preparing a world-record offer for the 23-year-old Portugal forward once his participation in the European Championship finals is over.

Sources in Madrid indicated last night that Real will offer United a fee in the region of £60 million for Ronaldo after Portugal are eliminated from the tournament, or, if they reach the final, after June 29. Ramón Calderón, the Real president, is said to be delighted by the developments of the past three weeks, with Ronaldo voicing his long-suspected desire to move to the Spanish champions. Real hope that the player will force United’s hand by requesting a transfer when his involvement in the tournament is over.

There is a growing realisation at Old Trafford that United may have to start planning for life without their outstanding player in the long term, given his incessant and brazen flirting with Real, but the Barclays Premier League club maintain that he will not be sold this summer, a stance that was illustrated yesterday when they carried out their threat to report the Spanish club to Fifa. David Gill, the chief executive, wrote the letter in which he spelt out his deep dissatisfaction at the manner in which Ronaldo has been unsettled by repeated public comments from Calderón and Bernd Schuster, the Real coach.

A statement on the United website read: “On May 27, 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 counsel and the club feels it has no alternative but to make a comment to the world governing body, which it has done. The precise content and nature will remain confidential.”

It is a remarkable step for United to take, but it is also one that Sir Alex Ferguson, the manager, had suggested would be futile. Fifa’s regulations on the matter are vague and United appear to have no hard evidence of the “illegal approach” that they suspect has been made to Ronaldo via Jorge Mendes, his agent.

It is also a complaint that leaves United open to accusations of hypocrisy. In August 2006, Bayern Munich threatened to report United over a similarly public pursuit of Owen Hargreaves, the England midfield player. Although the German club’s threat was never carried out, United could hardly be said to have dropped their interest when they were asked to, with Ferguson continuing to stalk the player until he finally moved to Old Trafford the next summer. Previously, PSV Eindhoven had accused United and Ferguson of arrogance over the way they conducted bids to sign Jaap Stam, Ruud van Nistelrooy and Arjen Robben.

A good deal of United’s frustration is with Ronaldo and Mendes, but, rather than risk antagonising the player, the club’s hierarchy have directed their anger at Real. Rio Ferdinand, the United defender, summed up the sense of despair at Old Trafford, from boardroom to dressing-room, when he questioned why Ronaldo would want to leave the European champions. “I think you would have to ask the question that everyone really wants to ask Ronnie,” Ferdinand told Sky Sports News.

“I was talking to David Beckham the other day and he was saying how it was crazy that he had left United on a winning note and it took him so long to win something over there [at Real], so sometimes the grass isn’t greener. But Ronnie is his own man, the lads at the club love playing with him and long may that continue.

“The manager is first-class in those situations and he’s had massive decisions to make in the past and so whatever the manager goes with, the players will be standing 100 per cent behind him.”