Borussia Dortmund sporting director Michael Zorc has played down speculation that Manchester United have made a bid for defender Mats Hummels.

On Wednesday, Sport Bild reported Manchester United have made a first bid for the German center back with the paper, citing sources in England, reporting that Louis van Gaal had tabled a €30 million offer.

"I can't confirm that," Zorc told Bild on Thursday, while Hummels added: "I don't want to comment on it all the time. I've done that a few weeks ago, and that has to be enough."