Wollongong councillors highlighted this issue on Monday night, during their first online meeting, and passed a motion to make it clear that the city's beaches must not be used by outsiders.

Part of a mayoral minute, the push was led by Cr Gordon Bradbery, who said NSW health rules made it clear that Illawarra beaches were "for our residents only".

Travellers using Illawarra beaches - from Wollongong's northern suburbs down the Shellharbour surf spots - have been highlighted by residents in recent weeks. In some places - like Coledale, Thirroul, Bulli and The Farm, at Killalea - people have installed makeshift signs to try to warn others away.

Unlike beaches in Sydney, which are closed to the public, beaches in the Illawarra remain open for exercise - including walking and swimming - as long as distancing rules are followed. However, they are not patrolled by life savers, and must not be used for gatherings of any kind.

Despite a strong push this week from NSW Police to stamp out unnecessary travel, Liberal councillor Leigh Colacino said he had seen Sydneysiders using beaches like Stanwell Park and other northern suburbs.

"I've got a lot of people in the northern suburbs who are doing their best to maintain safe distancing, but when people are coming down and making use of the beaches here because they are not allowed to do it where they live makes it extremely difficult," he said.

"If we're not careful, we're going to go to level four restrictions, where we're not allowed to even come out of our houses."

"People who want to visit their areas over Easter have to realise this is not a holiday option, it's a recipe for disaster."

Labor councillor Jenelle Rimmer agreed, saying "our city is not accepting visitors".

"Please keep us in mind for later in the year, but now is not the time," she said.

"For people living in nearby places, such as South Western Sydney, it is tempting to drive down here for the day with the thought to use our coastline but that's not what is best for our community. Please exercise in your own local community."

Greens councillor Mithra Cox said social distancing was important at beaches, but said she wanted to issue "a plea for the community not to become a vigilante mob".

"I have seen some ugly comments in our community about outsiders using beaches and whatever," she said.

"My question is 'how do you know that someone is an outsider?'

"It has been our multicultural communities that have copped the brunt of this more because there is a perception they are from Sydney, and that is not always the case.

"We've got 80 different language groups of people living here who are locals and who have the right the use out beaches.

"I would ask people not to assume that they know where someone comes from, and to judge people by their behaviour not their appearance. If people are keeping to themselves and moving about in small family groups and observing social distancing, then it's important to give people the benefit of the doubt and treat out fellow humans with kindness."

Around NSW, more and more beaches are being completely closed off to public access, as tourist hot spots try to keep visitors away.

Cr Bradbery said he hoped the council would be able to keep Wollongong beaches open for as long as possible, and said any decision to close them would be instigated by police.

"Police would make the call, and then the council would implement it in liaison with them," he said.

He reminded people that open spaces were available for use for essential exercise, and should not be used as a place to sit or meet to socialise in groups.

"I don't see why people couldn't momentarily pause and enjoy the vista, but the idea is not to make a day of it," he said.

"I don't think it should be a hard and fast rule, but at the beach, the Blue Mile for example, it's not the place to stop and have a conversation, even at arms length. Those things create bottlenecks which stops other people from being able to use the space."