A man is dead after being attacked by a large shark on Sydney's northern beaches.

Emergency crews were dispatched to Long Reef Beach shortly after 10am on Saturday, responding to reports a man had suffered critical injuries, police said.

He was retrieved from the surf and brought to shore but died at the scene.

Police have closed the beach and will liaise with experts to determine the species of shark involved.

Two sections of a surfboard have been recovered and taken for examination.

Beaches from Manly to Narrabeen have been closed pending further advice.

The identity of the man is to be confirmed.

Australian Associated Press

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