Dutch Prince Johan Friso, the second son of Queen Beatrix, suffered massive brain damage in an avalanche in Austria and might never regain consciousness, his doctors said Friday.

"It can't be said with certainty at this point whether Prince Friso will ever regain consciousness again," Wolfgang Koller, head of the trauma unit at Innsbruck University Hospital, told a press conference.

"In any case, a neurological rehabilitation will be required that will take months, if not years."

The 43-year-old father of two young daughters was caught in an avalanche while skiing off-piste with a friend in the posh Austrian ski resort of Lech a week ago.

He was quickly evacuated by helicopter to Innsbruck University Hospital but nevertheless spent some 25 minutes under the snow, according to the doctors.

"Due to the amount of time spent under the snow, his brain was not supplied with sufficient oxygen," Koller said.

"This resulted in a heart attack that lasted about 50 minutes. During this whole time, the patient had to be resuscitated," he said. "Fifty minutes of reanimation is very, very long, one might even say too long.

"Our hope was that the patient's mild hypothermia would provide some protection for the brain. This hope was not realised."

Doctors were able to do an MRI scan on the prince for the first time on Thursday and "it's clear that the lack of oxygen caused massive damage in the patient's brain," Koller said.

"The family of Prince Friso will now look for an appropriate facility for the rehabilitation," he added.

Kollar was giving the first official details on the prince's health since his accident last Friday.

Until now, the Dutch Royal House had limited itself to saying he was "stable, but not out of danger," with the hospital refusing to comment.

Queen Beatrix, 74, as well as the prince's wife Mabel Wisse Smit and his two brothers, Crown Prince Willem-Alexander and younger brother Prince Constantijn, were spotted arriving at Innsbruck University Hospital on Friday to visit him.

The Dutch royal family was vacationing in Lech, where it regularly spends its skiing holiday, when the accident happened, and members of the family have made daily visits to the prince's bedside.

Although the second son of Queen Beatrix, Johan Friso is no longer in line for the throne after he married in 2004 without the government's permission.

Austrian newspapers also reported Friday that Queen Beatrix had extended her stay in Austria for another week due to her son's accident.

A Dutch government statement said Prime Minister Mark Rutte had spoken to the queen and Johan Friso's wife by phone and had assured them the country "shares the royal family's pain at this time of worry and sorrow".

He also called on people to "respect the privacy of the prince and his family" and allow them to digest the latest news from the doctors "with serenity and in private."

The statement also quoted Queen Beatrix saying the royal family was "touched by the many reactions and expressions of support over the last week".

An experienced skier, Prince Johan Friso had been out with an Austrian friend on February 17 when he was buried under an avalanche in the resort in western Vorarlberg province.

The friend, whom local media have identified as the director of the hotel in Lech where the Dutch royals are staying, was equipped with an avalanche airbag and escaped unscathed.

At the time, the avalanche alert level at the time was at four, the second highest.

Vorarlberg prosecutors have now launched a routine investigation into the accident and what or who might have caused it.