Police in the Blue Mountains said they were hoping to fly family members in the UK to Australia to support the survivors.

Acting Superintendent John Nelson said the 15 year-old girl was in hospital with shock.

“We’ve focused on caring for her while the best medical care is given to her mum and a brother,” he told the Sydney Morning Herald.

New South Wales National Parks, which is in charge of the mountainous terrain west of Sydney, confirmed that the scenic walking track, which begins at Wentworth Falls, had been inspected only days before Monday’s tragedy as part of a routine assessment programme.

New South Wales Ambulance acting chief superintendent Stewart Clarke said the “freak accident” had been a heartbreaking experience.

He described the scene as “exceptionally confronting, especially when you start involving children.”

The area is famous for its 300 feet waterfall which gives the village of Wentworth Falls its name.

There has been heavy rain in the area over the past few weeks which may have added to the ground’s instability.

A Foreign, Commonwealth & Development Office spokesman said: “We are providing consular support to the family of a British couple and their children following an incident in Australia.”