Newcastle City Council's lifeguards are scouring the city's coastline for a fourth day, after a five-metre great white shark was spotted in the area again on Monday.

It was first seen on Saturday afternoon between Bar Beach and Merewether, and then again on Sunday near Nobbys.

On Monday afternoon, people on Stockton and Nobbys breakwalls spotted the shark swimming just metres from fishermen.

The city's beaches have been closed since Saturday, and Nobbys Beach inspector Paul Bernard said lifeguards have been out since first thing this morning.

People on Stockton and Nobbys breakwalls spotted the shark swimming just metres from fishermen yesterday. ( ABC News: Dan Cox )

"We're going to again reassess the conditions, and liaise with our bosses, and the other lifeguards up and down the coast," he said.

"We'll be out patrolling.

"Hopefully, possibly, the [region's rescue] helicopter will fly by as well and some decisions will be made there from what we come up with.

"The jet ski will be out and the guys have all got their binoculars.

"I think they're pretty much sewn to their heads at the moment."

Mr Bernard said the beaches will be closed until lifeguards are confident the shark has gone.

"This shark can move quite quickly, and it can disappear and pop up in various places," he said.

"Unfortunately, we have to take maximum caution and make sure people are staying out of the water on all of our city's beaches at the moment.

"It's that time of year when people want to be on our coastline and enjoying what Newcastle has to offer.

"We do still have the Newcastle ocean baths and Merewether ocean baths facilities open."