‘Debris balls’ have again washed ashore along the New South Wales coastline, leading to the closure of a beach until further notice.

The balls were found at The Entrance Beach; Grant McBride Baths, The Entrance; Blue Bay Beach; Toowoon Bay Beach; North Shelly Beach; Shelly Beach; and Blue Lagoon Beach.

The debris balls were grey in colour and vary in size from 10-40mm.

Thousands of balls washed ashore in Sydney last October, leading to the closure of two beaches. Testing the following month revealed the balls – believed to be made of tar – were made up of “fatty acids, petroleum hydrocarbons, and other organic and inorganic materials”, the NSW Environment Protection Authority confirmed.

The Central Coast Council yesterday advised locals to avoid the affected beaches until further notice and not to touch the material.

Grant McBride Baths was temporarily closed until further notice.

Grey 'debris balls' on a beach in NSW.

Testing was underway to determine its composition and origin.

“Debris balls washed ashore could be from a variety of sources or locations such as stormwater, sewerage networks, ships from local or international locations,” the council said.

“Council is taking a precautionary approach in managing a potential risk of these items.”