Popular Sydney rock formation 'could collapse at any time' Published duration 24 June 2015

image copyright NSW National Parks image caption Locals and tourists have performed stunts close to the edge of the unstable rock formation

A photogenic rock formation south of Sydney could collapse without warning, according to authorities.

Wedding Cake Rock is a popular tourist attraction that was recently closed to the public.

Last year, a university student died after falling from it and images of stunts performed on its edge have been widely shared on social media.

Authorities said an assessment confirmed fears the formation could collapse into the ocean.

NSW National Parks and Wildlife Service spokesman Gary Dunnett said the rock, which is in the Royal National Park about 30km (18 miles) south of Sydney, was closed several weeks ago for safety reasons.

A geotechnical assessment has now confirmed it could collapse at any time in the next 10 years.

image copyright NSW National Parks image caption The soft sandstone is gradually crumbling into the sea

The assessment included a photographic survey of the underlying rock strata using a drone, the service said in a statement.

It found the rock was "precariously balancing on the edge of the cliff", Mr Dunnett said.

"Usually when you get a geotechnical assessment, you'll get a probability of something happening within the next thousand years," he said.

"To get one back telling you that collapse is likely within the next decade is really unusual."

image copyright NSW National Parks image caption The site is popular with locals and tourists, some of whom have signed their names on the rock

Mr Dunnett said the service was working on a plan to allow visitors to view it safely.

Last year, French student Fabien Ardoin died after falling from the rock, according to local media.

Photos posted on social media show people doing handstands near the rock's edge, about 50m above the sea.