The helicopter belonged to Bristow Norway, the company's country manager, Heidi Wulff Heimark, told daily Stavanger Aftenblad.

Energy group Equinor said the helicopter was a search and rescue aircraft normally serving platforms at the company's Oseberg oil and gas field in the North Sea.

The helicopter was a Sikorsky S-92 model and was on a search and rescue training mission at the time of the accident, a police spokesperson told reporters, adding it was too early to say what had caused the crash.

The area had been experiencing high winds at the time of the accident, a rescue service official told broadcaster TV2.