The man was lying on his board about 20 metres from a large group of surfers off Redhead beach about 4.45pm yesterday when he was attacked by what was believed to be a bull shark.

The shark took a large chunk out of his thigh and dragged him under water, witnesses in the surf said.

Horror day on beaches

The man was able to shake himself free and get to the surface where he screamed for help while trying to get back on his board and paddle to safety.

Several surfers came to the man’s aid and helped him catch a wave into shore where lifeguards were waiting to begin treating him for his wounds.

Paramedics transported the man to the John Hunter Hospital.

The victim, Glen Folkard, of Whitebridge, also known as ‘‘Lenny’’, is 44 and owns Downunder Tattoo at Charlestown.

A Hunter New England Health spokeswoman said the man had suffered deep cuts to his upper thigh and was in a stable condition last night.

Lifeguards immediately evacuated surfers and swimmers and said they were closing the beach indefinitely.

Read about one family's love affair with Redhead Beach here.

Nathan Visscher, among several surfers who came to the man’s aid, said Lenny was furthest out in a large group of about 15 surfers.

‘‘He just started yelling ‘‘help, I need help’’,’’ Mr Visscher said.

‘‘I saw a trail of blood coming from him and then his board popped back up.’’

Another surfer, Tony James, said he saw the shark follow the man and circle him while he was trying to get to safety.

‘‘It’s just hit him and took him under for a bit,’’ he said.

‘‘He’s managed to get to the surface but I saw it start to follow him.’’