Two celebrated filmmakers working on a documentary with Oscar-winning director James Cameron and National Geographic have died in a helicopter crash in Australia, according to the media group.

Andrew Wight, 52, and Mike deGruy, 60, both longtime colleagues of Cameron, were killed when their helicopter crashed at a rural airstrip south of Sydney, National Geographic said a statement on its website.

According to local media reports the pair were in Australia working on a feature-length documentary about Papua New Guinea.

Wight recently co-produced the feature film "Sanctum 3D" with "Avatar" and "Titanic" director Cameron, after accompanying him on six deep-ocean documentary expeditions.

DeGruy, an Emmy award winning diver and submarine pilot with 30 years of experience in ocean filmmaking, was director of undersea photography for Cameron's "Last Mysteries of the Titanic".

Cameron said the pair had died "doing exactly what they loved most, heading out to sea on a new and personally challenging expedition."

"They were passionate storytellers who lived by the explorer's code of humour, empathy, optimism and courage," Cameron said in the National Geographic statement.

"Their deaths are a tremendous loss for the world of underwater exploration, conservation and filmmaking."

Though unable to confirm their identities, police said two men -- a pilot from Melbourne and male passenger from America -- died at the scene of a helicopter crash at Jasper's Brush, south of Nowra, on Saturday afternoon.

Emergency services arrived at the scene to find the helicopter "well alight", police said.

"Witnesses have told police the helicopter crashed shortly after taking off," police said.

National Geographic said Wight was the helicopter's owner and pilot.

A friend told Melbourne's The Age newspaper that Wight was "James Cameron's right-hand man for years and knew him intimately."