The attacking midfielder has attracted a wide array of suitors with his performances this year and Sir Alex Ferguson's side are thought to be leading the chase
The 19-year-old played a pivotal part in Borussia Dortmund's title-winning campaign last season and is expected to feature for Germany at this summer's European Championships.
And, according to Hebel, the talented midfielder is being courted by some of Europe's top clubs.
"I think in Europe all the top clubs are interested in Mario," Hebel told the Daily Mail.
"I can confirm that I have had contact with Juventus and Manchester United, but not only them."
One potential stumbling block behind any such move is the player's hefty price tag, which Hebel indicates Dortmund won't budge on.
"I don't know if he'll go away after this season, you should ask Borussia. But I think that they will not let him leave for less than £33 million.
"He still is very happy at Dortmund, though now he is injured."
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