9 Sydney beaches are closed after a mysterious ball-shaped piece of debris washed ashore

Nine beaches in Sydney, Australia, have been closed after a mysterious ball-shaped piece of debris washed ashore.

The discovery of the marble-sized balls comes a few months after the same incident in October of last year, where thousands black balls cleaned it led to the closure of Bondi Beach, among other popular tourist spots.

In a Facebook post, the Northern Beaches regional council warned the public to avoid Manly, Dee Why, Long Reef, Queenscliff, Freshwater, North and South Curl Curl, North Steyne and North Narrabeen beaches.

It also advises people not to travel “essentially” until further notice while clean-up operations continue.

The New South Wales Environmental Protection Authority confirmed in a statement that it was examining the debris and advised the public not to touch it.

The agency highlighted the similarities between these balls and those found last year, which are mostly composed of petroleum hydrocarbons but also contain traces of man-made waste.

Although the origin of the debris has not yet been clarified, the agency said at the time that it was looking at many possible causes, such as the discharge of dirty water and shipwrecks.