The former world champion said he was "sad and disappointed" at having to shelve plans to race for Ferrari, after a neck injury sustained in a motor cycle accident forced him to rethink his plans to return to Formula One.

"This is a very sad moment for myself," Schumacher told a news conference in Geneva, one day after announcing that he was cancelling his plans due to fitness concerns.

Schumacher was set to replace Felipe Massa in the Ferrari cockpit at Valencia after the Brazilian was injured during qualifying for last month's Hungarian Grand Prix. But he had to get the all-clear from doctors first before he could return to the sport.

"We have prepared very seriously, done as much as we could from our side, but we always said that I would do the job on condition I was ready for it, and sadly I couldn't fulfill this," Schumacher said. "I'm very disappointed not to do what I was looking forward doing and that's all I'm thinking about."

Schumacher said he was too disappointed at present to contemplate a return to Formula One later this year or in 2010. There had been media speculation that he could return for the Italian Grand Prix in Monza on Sept. 13 or next season.

"Speculation in this business is pretty natural, the fact is that I'm disappointed I'm not able to do what I looked forward to do ... that's how I feel for now," Schumacher said.

But the 40-year-old German and his doctor, Johannes Pfeil, refused to completely rule out a comeback at a later date, leaving a glimmer of hope for thousands of Ferrari fans who had been eagerly awaiting Schumi's dream comeback.

Doctor's orders

The neck injury he sustained in a motorcycle accident in February and medical exams after test runs in a Ferrari at a circuit in Italy in recent weeks showed that Schumacher had not recovered enough to withstand the strains of motor racing.

"The consequences of the accident were the worst Michael has had in his career," Schumacher's doctor revealed at the press conference.

Schumacher sustained fractures to the base of his skull, vertebra and a rib in the motorcycle accident on a racing circuit. Although completely healed, the bone still could not handle the g-force stress caused behind the wheel of a Formula One car, Pfeil said.

Schumacher admitted it was part of his nature to drive Formula One, jump out of planes and ride motorcycles but added that he had no regrets about retiring at the end of the 2006 motor-racing season.

nrt/AFP/Reuters/dpa
Editor: Nancy Isenson