Michael Schumacher has "moments of consciousness and awakening", his spokesman said on Friday - a sign of progress months after the Formula One legend suffered devastating brain trauma in a skiing accident.

Doctors put Schumacher in a medically induced coma after the Dec 29 accident in which he slammed his head on a rock while skiing at the French resort of Meribel with his son and friends, and little has filtered through since about his condition.

"Michael is showing progress; he shows moments of consciousness and awakening," Sabine Kehm said in a statement.

The 45-year-old remains in hospital in Grenoble, France, where he underwent two operations to remove life-threatening blood clots before being comatized.

His family said at the end of January that drugs used to keep him in his deep sleep were being reduced with a view to returning him to consciousness.

"We are on his side during his long and difficult fight, together with the team at the hospital in Grenoble, and we remain confident," Kehm said on Friday.

There have been previous signs of hope for the seven-time world champion, but Schumacher's family has requested that all such speculation be greeted with caution.

In February, his friend and former Ferrari teammate Felipe Massa was quoted as saying that Schumacher appeared to respond to him during a bedsite visit.

"He is sleeping; he looks normal and he showed a few responses with his mouth," Massa told the German tabloid Bild.

Last month, Schumacher's family said they were confident the racing legend who defied death more than once on the track would pull through.

"There sometimes are small, encouraging signs, but we also know this is the time to be very patient", Kehm said in a statement at the time.

"It is very difficult for all of us to comprehend that Michael, who had overcome so many precarious situations over the years, has been injured so terribly in such a banal situation," the statement read.

Schumacher survived a motorbike accident in Spain in 2009, during which he suffered head and neck injuries but was released from hospital after just five hours.

And even after retiring from the high-risk world of racing, he kept pursuing other dangerous hobbies as the holder of a pilot's license, an accomplished motorbike rider, parachutist, skier and mountain climber.

Kehm once again asked that the privacy of Schumacher's wife Corinna and their two children be respected, while thanking well-wishers for their support.

"We again ask for understanding that we do not intend to disclose details.

"This is necessary to protect the privacy of Michael and his family, and to enable the medical team to work in full calmness," Kehm said.

The news of an improvement in Schumacher's condition was greeted with relief by the sport's current top German drivers taking part in this weekend's Bahrain Grand Prix.

"Very happy to hear good news about Michael here at Bahrain," tweeted current world championship leader Nico Rosberg, who was Schumacher's teammate on Team Mercedes from 2010 until 2012.

"It's fantastic to hear," Rosberg told a news conference later. "We know that his family would be very careful before releasing such good news. I hope he will continue to progress."

Current world champion Sebastian Vettel said the latest update was good to hear.

"It's great news for his family and for Formula One," said Vettel.