Hamburg, Aug 11: Michael Schumacher will not return to Formula One racing due neck problems from a motorbike accident in February, he said on his website Tuesday.

The seven-time world champion Schumacher, 40, was set for a sensational return to take the place of injured Ferrari driver Felipe Massa for several races, starting with the European Grand Prix on August 23, in Valencia, Spain.

"Yesterday evening, I had to inform Ferrari President Luca di Montezemolo and Team Principal Stefano Domenicali that unfortunately I'm not able to step in for Felipe," Schumacher said.

"I really tried everything to make that temporary comeback possible, however, much to my regret it didn't work out.

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

Schumacher said he had fractures in the area of the head and neck in the bike accident and that "my neck cannot stand the extreme stresses caused by Formula One".

Massa sustained severe head injuries in a crash during qualifying for the Hungarian Grand Prix in Budapest July 25. He is currently recovering for an indefinite period in his native Brazil.

No details have been given yet, but Ferrari are now expected to give the car to one of their test drivers, Luca Badoer or Marc Gene, now that Schumacher is ruled out.

Schumacher's planned comeback was announced a few days after Massa's crash and caused a huge sensation in the motorsport world.

Ticket sales for the Valencia race soared after the news broke, even though Schumacher's camp always said the return was pending the medical.

Schumacher, who retired from racing in 2006, underwent a thorough fitness regime with doctors in Bad Nauheim, Germany, but said early on that the neck was giving him problems.

He said he was ready for the challenge of returning, but had to realise in the end that a comeback (at this time) was impossible due to the ongoing neck problems.

"I am disappointed to the core. I am awfully sorry for the guys of Ferrari and for all the fans which crossed fingers for me. I can only repeat that I tried everything that was within my power. All I can do now is to keep my fingers crossed for the whole team for the coming races," said Schumacher.