David de Gea
Rio Ferdinand has warned Manchester United against selling David de Gea to Real Madrid this summerGetty

Manchester United legend Rio Ferdinand has warned the Red Devils against letting David de Gea leave this summer, as he feels that the Spaniard's departure will put an end to the Old Trafford club's title hopes for the 2015/16 campaign.

The Spanish international stopper has been heavily linked with a move to Santiago Bernabeu this summer, and according to Daily Mail, the Spanish capital club are preparing a fresh £25m ($16.1m) bid to sign De Gea before the start of the La Liga campaign in two weeks time. But according to the report, the Red Devils will demand £35m for their 2014/15 player of the season.

Louis van Gaal is reluctant to let the goalkeeper leave the club, but is aware that the interest from the 10-time European champions has turned his number one's head. The Spanish 'keeper was dropped from the squad for United's opening Premier League encounter against Tottenham, with the manager citing a lack of focus on the goalkeeper's part.

However, Ferdinand has urged the 20-times English champions to hold on to De Gea for another season, as he believes that the former Atletico Madrid star can help them challenge for trophies this season.

The 24-year-old 'keeper has just one year remaining on his current deal and has refused to sign an extension, therefore putting the club in danger of losing him on a free transfer next season.

"If Manchester United lose David De Gea they can forget about a title challenge," Ferdinand wrote in his column for The Sun, according to Fox Sports.

"A club like United cannot allow a keeper of De Gea's stature to leave because the transfer fee they receive from Real Madrid will not make up for missing out on major trophies."

"Should David choose to walk out the door next summer, when his contract expires, then so be it. But United don't need the cash and they can afford to be strong. I know De Gea well from my days playing with him at Old Trafford and he is too professional to throw the towel in and sulk," he explained.

"He might not like the decision, but it's not the biggest hardship in the world to have to play for Manchester United for another year," the former United defender added.