In the past 24 hours, four Australian states have imposed COVID restrictions.

In the past 24 hours, four Australian states have imposed swift and strict restrictions to slow the spread of coronavirus.  

Darwin, Perth, Brisbane and Sydney are all facing new challenges with the emergence of COVID-19 in the community.

While Darwin and Greater Sydney are now in lockdown, Brisbane and Perth have seen the quick introduction of restrictions. 

Here's everything you need to know. 

Darwin enters 48 hour snap lockdown. 

Northern Territory Chief Minister Michael Gunner announces 48 hour lockdown for Darwin and surrounding areas. Image: Getty. 

Darwin and surrounding areas have entered a 48-hour lockdown following four new COVID-19 cases linked to a central Australian mine, Northern Territory Chief Minister Michael Gunner announced on Sunday.

Mr Gunner warned this outbreak represents the Northern Territory's biggest crisis since the beginning of the pandemic and says the cases involve the highly contagious Delta variant. 

It comes as a man who works at Granites Gold Mine, 540km northwest of Alice Springs, tested positive on Friday afternoon. 

The diagnosis has seen 754 people go into isolation on the mine site, however there is concern for a further 900 workers who have already left the gold mine. 

Of 244 potentially exposed people who remained in the NT, Mr Gunner says 15 who arrived in Darwin since Friday remain unaccounted for. 

The lockdown began at 1pm on Sunday local time.

Residents within the Darwin, Palmerston and Lichfield local government areas are only permitted to leave home for medical treatment, to obtain essential goods and services, for work considered essential, one hour of exercise a day or to provide care.

Anyone who leaves home must wear a mask.

Perth imposes new restrictions. 

WA Health Minister Roger Cook announces new restrictions for the Perth and Peel regions. Image: Getty. 

A Western Australia woman who visited Sydney and returned home has picked up COVID-19, prompting new restrictions including mask wearing indoors.

The woman was in the Bondi area of Sydney earlier this month. It is assumed the woman has the Delta virus variant.

On Sunday, WA Health Minister Roger Cook said Perth and Peel residents would immediately be required to wear masks indoors and on public transport.

Public events will be restricted to 150 people, while Sunday's AFL match between West Coast and Western Bulldogs will go ahead without crowds. The Chicken and Beer Festival in Perth scheduled for Sunday has been cancelled.

A 30-person limit is in place for private gatherings and Perth and Peel venues must adhere to the "two square metre" rule.

Travel to Western Australia's remote Indigenous communities will also be restricted.

Mr Cook didn't rule out lockdown as a future necessity, with the current restrictions to remain in place for at least three days.

Two new local cases in Queensland spark new restrictions. 

Queensland has brought back some restrictions. Image: Getty.

A couple who have been active in the Brisbane community for several days have tested positive to COVID-19. The new cases are believed to be part of the Brisbane cluster linked to a Portuguese restaurant, and not the Sydney outbreak. 

While the couple didn't attend the restaurant, Chief Health Officer Jeannette Young said, one is friends with people who did. That person did not develop symptoms, but got tested because they were working at Brisbane Airport's Direct Factory Outlet, which was earlier listed as an exposure site. 

"We are going to deem them as infectious in the community from the 20th of June," Dr Young said on Sunday. 

"They've been to a lot of sites throughout the community which we'll put up on our website, several gyms (and) several shopping centres."

If the new cases are linked to the existing Brisbane cluster, involving the Alpha variant, they would take that outbreak to nine known cases.

In light of this, Queensland has reintroduced restrictions for two weeks from 6:00am Monday.

Pubs, restaurants and cafes will revert back to a one-person-per-two-square-metres rule, while private gatherings at homes will be limited to 100 people, including children and infants.

Dr Young said there is "a lot happening" in the state, and urged anybody with symptoms to get tested as soon as possible.

"That is just critical," she said.

Sydney enters a 14-day lockdown.

NSW Premier Gladys Berejiklian has plunged Sydney into lockdown for 14 days. Image: Getty. 

On Saturday, NSW Premier Gladys Berejiklian sent more than five million people in Greater Sydney into a 14-day lockdown as health authorities try to regain control of a coronavirus outbreak that has ballooned to 110 cases.

Residents of Greater Sydney, the Blue Mountains, the Central Coast and Wollongong will only be able to leave home for essential purposes.

Those reasons include work, to shop for essential items, to seek medical care, for exercise or for caregiving or compassionate reasons.

Anyone in NSW who has been to Greater Sydney since June 21 is also being asked to stay at home for the entire lockdown period.

The snap lockdown comes after another 30 new virus cases were recorded in NSW on Sunday and exposure venues spread beyond the Eastern Sydney hotspots to the Northern Beaches and Western Sydney, where people have potentially been infectious for days.

Exercise outdoors is allowed in groups of up to 10, and COVID-safe funerals can proceed with up to 100 people.

Weddings are allowed to go ahead on Saturday and Sunday with restrictions in place, but must be cancelled from Monday.

Restrictions have also been introduced for regional NSW, as Chief Health Officer Kerry Chant has said the virus is spreading too fast.

"Despite testing numbers being quite high and the contact tracers getting in contact with people rapidly, what we're seeing is by the time we've got there and uncovered the chains of transmission, we have a number of people infectious in the community," Dr Chant said.

Meanwhile, following an investigation into how a Sydney limousine driver at the centre of the city's coronavirus outbreak was not vaccinated, Police Commissioner Mick Fuller confirmed on Saturday there was insufficient evidence to establish that either the driver or his employer breached any public health orders. 

Feature image: Getty.

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