More than 1100 people in NSW have been ordered into a five-day “lockdown” and will be tested for COVID-19 after visiting Western Australia, while the virulent British strain is potentially circulating in Perth.

On Sunday it was revealed a hotel quarantine security guard in Perth had tested positive for the virus and had visited more than a dozen venues since January 25 while potentially infectious.

About two million people in Perth and the nearby Peel and South West regions of WA have been plunged into a five-day hard lockdown and several states rushed to close borders to WA.

The NSW border has remained open but anyone arriving from the locked-down areas since January 25 is required to follow the same stay-at-home restrictions as they would have faced had they stayed in WA.

They are also required to be tested for COVID-19 within 48 hours of arriving in NSW

Anyone who refuses to be tested faces a 14-day mandatory quarantine period.

The recent arrivals locked-down in NSW are allowed to leave home with one other person to exercise for an hour each day, to shop for groceries and essentials, or seek medical attention.

But they must wear a face mask while doing so, unless exercising outside on their own.

Those restrictions are due to expire at 9pm (AEDT) on February 5 – the same time as the WA lockdown ends.

A NSW Health spokesman said health officials would be “checking in” with people to make sure they understood and were following the requirements.

He also urged anyone who might be confused by the rules to call NSW Health.

Stewart Marshall, 26, will return to Sydney on Tuesday and admitted he was “a little confused” about the state’s rules.

He had been in Perth since December visiting family and friends and said it had been tough deciding when to leave.

“It’s awkward timing because you don’t know what will become of it,” he said.

“You’re kind of waking up every day and wondering what the case numbers will be and wondering what NSW might do.

“I’m hoping NSW don’t introduce any stricter measures if there’s new cases in WA.”

Fearing he might become stuck in Western Australia, Mr Marshall decided it was time to head home.

“Either way, I’m going to be having a stint in isolation, so I feel like it’s unavoidable,” he said.

“I’m not stoked about it, but it is what it is.”

There were no new cases of COVID-19 in WA on Monday after 3200 tests were conducted on Sunday.

Dr Danielle McMullen says WA’s virus testing rates need to lift. Photo: AMA

The NSW President of the Australian Medical Association, Dr Danielle McMullen, said recording zero cases in WA should not be cause for confidence until testing rates increased.

“WA really needs to be doing as much testing as possible … certainly 3000 doesn’t sound like many,” she said.

Passengers who arrived in Sydney on a flight from Perth on Sunday night were screened for symptoms and asked if they had attended any of the same venues as the security guard.

None of the passengers reported being at those venues.

On Monday, NSW Premier Gladys Berejiklian defended keeping the NSW border open to WA.

“I want to make clear that NSW has a standing policy on keeping its borders open, and that’s what we’ll continue to do,” she said.

“It’s a manageable situation at this time, and that’s why we will be keeping our borders open.”

-ABC