Manchester United have been warned off Germany World Cup winner Mats Hummels this summer after Borussia Dortmund manager Jurgen Klopp told the 20-time English league champions to "forget" signing the centre-back.

Since the departure of Nemanja Vidic and Rio Ferdinand, Louis van Gaal has been linked with bringing the Dortmund defender to Old Trafford.

However, Klopp has reacted angrily to suggestions Hummels is ready to leave Dortmund this summer and urges United to look elsewhere to calm their defensive problems.

"I can assure everyone that there are no signs that those two players want to leave. Marco and Mats will play for us the next season," Klopp told German TV.

"What are we talking about today? Mats to Manchester United? For how much? €20m (£15.8m)? With those kind of sums can you forget that straight away."

With Shinji Kagawa and Robert Lewandowski having both left Dortmund in recent summers, Klopp had good reason to believe that Hummels could become the latest high-profile exit after staring in Germany's run to a fourth World Cup.

On Monday, United saw another experienced player in Patrice Evra leave the club for Juventus and though Luke Shaw has joined from Southampton, Van Gaal is in desperate need of some additional defenders.

Though the former Netherlands coach wants to give his current squad a chance to impress, ahead of United's first pre-season friendly against LA Galaxy on Wednesday, executive vice-chairman Ed Woodward says new signings are imminent.

Ander Herrera and Shaw represent United's intent to return to the higher echelons of English football after a worst ever finish in the Premier League era saw them miss out on qualifying for the Champions League.

Van Gaal has just six weeks to evaluate his squad and act upon it in the summer transfer window, with a centre back despite the presence of Phil Jones, Jonny Evans and Chris Smalling, expected to be a priority.