But United hit back at their old rivals by publishing a counter-statement on Tuesday evening.

The statement read: “Manchester United acts appropriately and efficiently in its transfer dealings. The club is delighted that its fan-favourite double Player of the Year, David de Gea, remains a Manchester United player.”

In their 443-word statement, Madrid claimed they had to wait until Monday - deadline day in Spain - to “open any channel of negotiation'” with United over De Gea.

After a deal had been struck for the transfer of De Gea, and Keylor Navas, who was to head in the opposite direction, Madrid claimed they sent United the contracts for the deal at 12.39 BST – over 10 hours before the window closed.

The Spanish giants then claim United made “minor modifications”, which were accepted. Madrid added that United did not reach agreement with Navas over his part of the deal until seven minutes before the window shut.

The result, they claim, was that United did not upload the details into FIFA’s Transfer Matching System (TMS) until 11pm exactly. That meant Madrid could not complete their part of the process and that is why the deal collapsed, according to the Spanish club.

United, however, insist the botched transfer was all Madrid’s fault.

In their statement, United angrily rejected the idea that they left it until the last minute to decide to sell De Gea.

“Manchester United did not seek contact from Real Madrid for the sale of David,” United said. “David is a key member of our squad and the club’s preference was not to sell.”

United also claim Madrid made an error in the last couple of hours of the window. They claim they sent the transfer documents for both players to Madrid at 8:42pm and received them back at 10:32pm, without De Gea’s “signatory page”.

United also claim Madrid made “major changes” to the documentation 20 minutes for deadline, which “immediately put the deals at risk”, according to the 20-time English champions. United insist they had still not received the requisite documentation for Navas’ transfer at this point either.

Finally, United claim they uploaded the relevant documents at 10:58pm, two minutes before the deadline.

The United statement added: “It is our understanding that the deals couldn’t happen because:

- Real Madrid didn’t upload David’s documents onto TMS in time (Manchester United did).

“(And) Real Madrid didn’t upload David’s documents to the Spanish league in time, per reports it seems some 28 minutes after the deadline.

“The fact that Manchester United filed the papers on time was acknowledged by the Football Association, who offered to support that claim in any discussions with FIFA. The club offered this assistance, as well as its own timestamped documents to Real Madrid but they have chosen not to go down this route.”

As two of the big powerhouses of world football, United and Madrid have often clashed throughout history.

The most controversial episode of the bitter rivalry came when United refused to sell Cristiano Ronaldo to Madrid in 2008. Then manager Sir Alex Ferguson hit out at the Spanish giants at the time, claiming they had tapped up his star player.

“You don’t think we’d get into a contract with that mob, do you? Jesus Christ. I wouldn’t sell them a virus,” the Scot famously said six months before admitting defeat and selling the Portuguese to Madrid.

Relations seemed to have improved when Madrid sold one of their star players at the time – Angel di Maria – to United last summer for £59.7million.

But that deal ended up being an embarrassment for United as they had to sell the misfiring Argentinian to Paris St Germain less than 12 months later.

For now, De Gea is in Spain preparing for the upcoming internationals against Slovakia and Macedonia.

Van Gaal has opted to leave De Gea out of his squad for the first six games of the season because he has not been mentally fit enough to focus, according to the United boss.

The Dutchman will have to decide over the coming weeks whether the former Atletico Madrid man can knuckle down and take the gloves off Sergio Romero, who has deputised for United’s two-time player of the year this term.

United’s next game is a week on Saturday at home to arch rivals Liverpool.