A section under the platform at the popular tourist attraction collapsed following recent wet weather.

Eurobodalla Council fenced off the site on Tuesday and erected signage advising people to avoid the immediate area.

A Council spokesperson said an urgent geo-tech review of the site was being arranged.

"This review will also include Australia Rock itself, which appears to have experienced some smaller rockfalls as well," the spokesperson said.

"Visitors to the rock can continue to view it from afar but should not go near it for their own safety."

Australia Rock, at Bar Rock lookout, is a popular photo opportunity due to its resemblance to the shape of Australia (without Tasmania).

It is one example of the Eurobodalla's ancient geological sites that include formations and folds of sandstone, siltstone, shale, granite and basalt - some dating back 510 million years.