Newcastle beaches could remain closed for a record six days with repeated sightings of a large great white shark again keeping swimmers out of the water.
The five-metre shark, first spotted on Saturday afternoon at Merewether Beach, could bite a person in half, Nobbys Beach inspector Paul Bernard told AAP.
"You don't get a second chance with these things," he said.
The shark was last seen by water police early Tuesday afternoon at Burwood Beach and has been sighted in an area stretching 10 to 12 kilometres.
"We've consistently seen the big one every day. Certainly it's the biggest shark we've ever had and it's hung around longer than any other shark," said Newcastle Council aquatic services co-ordinator Peter Withers.
Helicopters have also been combing waters off Newcastle but didn't spot the shark during a search late that same afternoon.
Overcast and warm weather combined with increased marine activity could be responsible for the shark's prolonged presence.
A Newcastle Council statement says lifeguards are working extending hours to ensure everyone has been warned about the dangers of going in the waters.
"We ask for everyone's cooperation in remaining out of the water at our beaches until lifeguards are satisfied that the shark has moved out of area waters," the council said in a statement.
"Our lifeguards emphasise that this great white shark is of a size that has not been seen before around Newcastle. It appears to be nearly full grown at an estimated five metres in length which would make its weight around 1700kg.
"Sightings have been across all beaches, from Stockton to Merewether. It is not safe for board riders to be out in the water, even close to shore, as sharks are known to move into the surf zone, hunting prey between where the surf breaks and the shoreline."