Michael Schumacher's former manager has slammed Bernie Ecclestone for comments about the F1 legend.

In an interview with Sport Bild, former F1 supremo Ecclestone said of Schumacher: "His problem was that he had no limits."

The 88-year-old was referring to incidents like Jerez 1997, when Schumacher turned in on his championship rival Jacques Villeneuve.

"The scandals brought a lot of publicity, but not the right kind," Ecclestone said ahead of F1's 1000th race in China this weekend.

Ecclestone also said Schumacher was wrong to return from retirement in 2010.

"It was good for formula one but not so good for him. But that's what I meant by him not knowing the limits," he said.

Willi Weber, Schumacher's former long-time manager, called Ecclestone's comments "stupid".

"As a racing driver, you have to go to and sometimes beyond the limit," he told Kolner Express newspaper.

"Nobody knew this better than Michael, who became the most successful racing driver of all time. Bernie knows it too," Weber added.

"The fact is that Villeneuve actually invited him to drive into him. I told Michael 'If you do it, do it right, just as Prost and Senna did a dozen times'.

"But he did it half-heartedly, because as a German he knew it was sh*t".

Weber also said Schumacher and Ferrari's success put Ecclestone and F1 "in a place they had never been before and may never be in again".

"And yet now he talks like that about Schumi who cannot speak for himself," Weber said.

As for Schumacher's return to F1 with Mercedes in 2010-2012, Weber revealed: "I actually advised Michael that he could not win, he could only lose.

"But he was simply inspired by the idea of succeeding again with his old friend Ross Brawn. The fruits were then harvested by Lewis Hamilton and Toto Wolff," he said.