Michael Schumacher has had to cancel his Formula 1 comeback as a result of the neck injuries he suffered in a motorcycle crash earlier this year.
In a statement issued on his website, Schumacher said that he told the team last night he was not fit enough to race as a replacement for the injured Felipe Massa.
"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," he 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 suffered a sizeable accident during a German superbike test at Cartagena in Spain on February 11 - which forced him to abandon entering motorcycle races. It had been hoped that the injuries he suffered in that crash would not impact on his F1 return, but medical examinations have indicated that problems remain.
"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," added Schumacher.
"That is why my neck cannot stand the extreme stresses caused by Formula 1 yet. These are the clear results of the examinations we did on the course of the past two weeks and the final examination yesterday afternoon.
"As there were no improvements after the day in Mugello, I decided at short notice on Sunday to do that thorough examination already yesterday.
"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."
Schumacher had been due to test an F2007 at Mugello in Italy from today, but there is now little reason for him to see through with that running.
It is not clear who Ferrari will now slot in as the replacement for the injured Felipe Massa, with the team having little more than one week to find a suitable driver.