Hundreds turned away from swamped Covid-19 testing stations in Sydney

Hundreds of people have queued for Covid-19 tests in Sydney, only to be turned away after testing centres were swamped.

There were 22 new cases of the virus confirmed in New South Wales yesterday, in outbreaks across the state.

Many residents in one south coast town are desperate to get tested after a fresh cluster emerged.

Meanwhile, the NSW premier insists she won't jump ahead of health advice by mandating the wearing of masks in public amid a growing Covid-19 case load.

NSW in the 24 hours to 8pm (11pm NZD) on Sunday recorded its highest daily number of Covid-19 cases in three months and will from Wednesday enforce tougher border restrictions for people wanting to enter the state from Victoria.

A border zone will be set up along the Murray River from midnight with all outstanding travel permits to be cancelled.

The state recorded 20 new Covid-19 cases on Sunday, including three linked to the 48-strong Crossroads Hotel cluster.

But Premier Gladys Berejiklian today said she wouldn't yet follow Victoria's lead by enforcing mask use in public but urged that people wear masks where social distancing was impossible.

She said social distancing remained more important.

"What NSW Health and myself are worried about most at this moment in time is what people are doing when they're entering hospitality venues ... you can't wear a mask when you're having a meal," Ms Berejiklian told 2GB radio.

"That's where the biggest risk is at the moment, indoor events.

"The health advice to date has served NSW extremely well and it's not for politicians to make this stuff up as we go."

Eight other new cases yesterday were linked to the Thai Rock restaurant in Wetherill Park and four to the Batemans Bay Soldiers Club on the south coast.

Ms Berejiklian said NSW had the chance to get ahead of the virus if residents socially distance over the next few weeks, and warned hospitality venues could face major penalties if they failed to ensure social distancing.

"We've seen numerous examples now where it only takes one person or two people to have the virus and then you end up having to contact 6000 people because of the flow-on effect," Ms Berejiklian said.

"This can get away from us very quickly which is why I'd rather everyone do the right thing now while we can still be in a position to control the spread."

There are 96 people being treated for the coronavirus in NSW, with two patients in intensive care - including a person in their 30s.

NSW Health yesterday afternoon also directed anyone who attended Our Lady of Lebanon Cathedral in Harris Park between July 15 to 17 to self-isolate for 14 days and come forward for testing after a confirmed case's visit.

NSW Police Commissioner Mick Fuller, meanwhile, yesterday warned the public against attending a Black Lives Matter protest planned for Sydney next week.

Mr Fuller says NSW Police will attempt to block the planned July 28 protest in the Supreme Court and urged the public to not be "selfish".