Seven-times world champion Michael Schumacher has cancelled plans for a temporary return to Formula One with Ferrari because of fitness concerns.

The 40-year-old was due to replace the injured Felipe Massa but with a neck injury sustained in a motorcycle accident earlier this year still causing him pain during testing, Ferrari have given the seat to experienced test driver Luca Badoer.

"I really tried everything to make that temporary comeback possible, however much to my regret it didn't work out," the German told his website (www.michael-schumacher.de).

"Unfortunately we did not manage to get a grip on the pain in the neck which occurred after the private F1-day in Mugello (last week), even if medically or therapeutically we tried everything possible."

Schumacher, who retired in 2006, had been expected to return for the European Grand Prix on Aug. 23 while Massa continued his rehabilitation from a fractured skull but the German conceded defeat in his battle to get fit for the Valencia race.

"The consequences of the injuries caused by the bike accident in February, fractures in the area of head and neck, unfortunately have turned out to be still too severe," Schumacher added.

"That is why my neck cannot stand the extreme stresses caused by Formula One yet. These are the clear results of the examinations we did ... over the past two weeks and the final examination yesterday afternoon."

Mercedes, who own 40 percent of the McLaren team and also provide engines to Brawn GP and Force India, said Schumacher's withdrawal was bad news.

"This is a bitter disappointment for everyone who was looking forward to Michael's comeback," Mercedes motorsport vice-president Norbert Haug told reporters.

"But health of course has priority over everything. That is clear," added German Haug.

BADOER REWARDED

Ferrari said Schumacher's withdrawal was a blow, before moving quickly to appoint Badoer as Massa's replacement.

The 38-year-old Italian started 49 races for Scuderia Italia, Minardi and Forti without scoring a point between 1993-99, his last competitive drive coming at the Japanese Grand Prix almost a decade ago.

"I'm very sorry about the problem that will stop Michael returning to racing," said Ferrari president Luca di Montezemolo in a statement.

"His return would surely have done Formula One good and I'm certain we'd have seen him fighting for victory again.

"In agreement with (team principal) Stefano Domenicali, we have decided to give Luca Badoer the chance to race with the team after many years of precious work in the role of tester."

Schumacher's return was seen as a major boost to Formula One in a scandal-ridden season dominated by breakaway threats, legal challenges and accusations of cheating.

European Grand Prix organisers would also have benefited from his comeback after seeing ticket sales rise in recent weeks.

"It is bad news. We had all taken it for granted he was going to be here and we were very pleased," said Jorge Martinez Aspar, vice-president of race organisers Valmor Sport.