A man has died after a shark attack at Tuncurry Beach on the NSW Mid North Coast.

Emergency services were called to the beach, next to Forster, about 11:20am after receiving reports a man had been bitten by shark while surfing.

NSW Police said they found the man, believed to be in his 50s, with "critical injuries to his upper right thigh".

They pulled him from the water and attempted CPR, but were unable to revive him.

The Mid North Coast Council has closed beaches from Black Head to One Mile at Forster.

Police said they will be working with the Department of Primary Industries to identify the species responsible.

Brian Wilcox from the local Surf Life Saving branch said the attack was "unprecedented".

"I can't recall ever having shark attack in this area," he said.

Mr Wilcox said a number of sharks had been spotted in the water since the attack.

"The process for Surf Life Saving now is to keep the beaches closed for 24 hours, we've already had a drone up in the air to see if we could spot some sharks in the area, there were a couple of sharks spotted, whether they were the one or not, who knows," he said.

Surf Life Savers will now conduct drone patrols around Tuncurry Beach for several days.