Surfer injured in fourth shark attack in Australian state in 48 hours

A surfer has been bitten by a shark, the fourth attack along Australia's New South Wales (NSW) coastline in under 48 hours.

The 39-year-old man "sustained a wound to his chest" after a shark bit his board on the Mid North Coast on Tuesday morning, police said. He has been released from hospital.

It follows three other attacks in Sydney over the past two days. All beaches in Sydney's northern area will remain closed until further notice, said police.

The attacks follow days of heavy rains, which NSW Superintendent Joseph McNulty had earlier said may have created a "perfect storm environment" for shark attacks. Rain flushes nutrients into the water, which can draw sharks closer to shore.

The attack on Tuesday took place near the Point Plomer campground, about 450km (279 miles) north of Sydney.

Steve Pearce, the chief executive of Surf Life Saving NSW, said the surfer was "very fortunate to not have sustained any serious injuries", ABC reported.

"We really strongly advocate that nobody swim or surf near river mouths because it's obviously an area where sharks congregate," Pearce said. "If it's dirty water I'd think twice about going in there."

A young surfer had a similarly lucky escape at Dee Why Beach in Sydney on Monday, but a shark attack at nearby Manly hours later left a 27-year-old with "life-changing" injuries. On Sunday, a 12-year-old boy was also critically injured when bitten at a popular Sydney Harbour beach.