Kubica suffered major injuries in a crash on a rally in Italy
The Renault team's doctor says injured driver Robert Kubica's recovery will take a "long time" following the injuries he sustained in a rally crash.
Kubica suffered a partially severed right hand and fractures in his right leg and arm in the accident last month.
Dr Riccardo Ceccarelli said it was "impossible" to predict when the Pole would be able to race again.
"This year, next year, three years? I can only say what I know. He's reacting well but it will take a long time."
And Ceccarelli said his progress had surprised the doctors at his hospital in Pietra Ligure, which coincidentally is one of Italy's leading centres for such injuries.
"Robert is getting better every day. I see that he is recovering physically and pyschologically very quickly," Ceccarelli said.
"This is not a surprise for us as we know Robert very well but it is a surprise for the doctor of the hospital.
Dr Riccardo Ceccarelli
“He is moving fingers, moving the wrist. That is positive, and we cannot predict anything else”
"They are satisfied how he is reacting to the surgery and the injuries that he has. We are happy with the strong reaction. These are positives things in a traumatic situation."
He added: "No one can answer when (he will recover) because we can only say that the surgeons did a great job.
"Robert is very strong and he is recovering in a good way. It is a question which is impossible to answer, the time is impossible.
"We have two positive aspects. The job done by the doctors and Robert who is strong. All the other things are impossible to say."
Ceccarelli said Kubica would stay in Pietra Ligure for the foreseeable future.
"They have specialist surgeons for the hand and there are some physiotherapists who are special for the hand," he said.
"They are providing the best assistance every day for hours so it makes no sense to move from there. We do not know when we decide to move as we don't know how the recovery will be.
"The body has a capacity to react which is different from person to person, so we follow day by day to understand what he needs."
The main concern remains over whether Kubica's right hand will recover sufficiently for him to be able to drive an F1 car again.
"He is moving fingers, moving the wrist. That is positive, and we cannot predict anything else," said Ceccarelli.
"The main fracture was in the arm and everything follows with the improvement of that, with the elbow and the hand.
"These are the main points of the injury, and what we have to follow with deep attention."