A Sydney tradie who was prevented from attending last weekend's anti-lockdown protest later left home after testing positive to coronavirus, police say.

NSW Police Commissioner Mick Fuller made the bombshell announcement during today's press conference where Premier Gladys Berejiklian also revealed 170 new community infections.

He initially said that the man had gone to work on a building site.

However, NSW Police later clarified that is what they were initially told during a compliance check at the 35-year-old man's house following his positive test result.

Subsequent inquiries revealed the man was not at work but was at a home at Constitution Hill.

"That sort of behaviour is exactly why we need strong health orders, law enforcement and defence [to] get the highest level of compliance," Fuller said.

"One person could spread the virus. All the workers [then] go home and spread it to their families."

Police say that on July 24 the man was stopped at Central Station while on his way to the anti-lockdown protest.

He was turned away by police and fined A$1000 for breaching stay-at-home orders.

The following morning, he tested positive for Covid-19 and was told to self-isolate.

However, Fuller said the tradie was caught out when police carried out a general compliance check and found he was not home.

George Thompson allegedly breached Covid protocols by travelling to Queensland. Photo / Supplied

More than 300 Sydneysiders were fined overnight, mainly for not wearing a mask.

Fuller warned people not to break the rules if they tested positive to Covid or were deemed a close contact.

"You are absolutely going to get a knock on the door and if you are not home, we will take action against you, whether that be criminal [charges] or a $1000 infringement," he said.

"If people do not listen, it puts us back into the lockdown and that is the key message."

The shocking revelation comes just days after another Sydney tradie was fined almost A$10,000 for flouting Covid-19 restrictions after his illegal entry into Queensland. He claimed he just "wanted to get out" of the locked-down city.

George Thompson, 26, was fined by Queensland Police this week after he flew from Sydney to Ballina airport earlier this month despite being deemed a close contact of a confirmed case by NSW Health.

He was picked up by his partner, 36-year-old flight attendant Malynda Gray, who brought him back into Brisbane.

The pair spent several days in the south-east Queensland community, allegedly providing false check-in information, before Gray tested positive to Covid-19.

After allegedly failing to co-operate with police, she eventually disclosed how she had contracted the virus.

Thompson was placed into hotel quarantine, where police allege he repeatedly opened the door to his room and verbally abused staff. As a result, he was fined almost A$10,000.

"I just wanted to get out of there," Thompson told 9 News. "Just let them think what they want because I don't really take it to heart."

No criminal charges have been laid against the pair.

Of the 170 new infections on Friday, more than 40 were in the community while infectious.

Premier Berejiklian said more than 95,000 people were tested in the latest reporting period.

"Obviously, today's number is considerably less than yesterday, but don't assume it won't be back up tomorrow because there are so many infectious in the community," she said.

"We expect to see those numbers bounce around."

Text by Erin Lyons, news.com.au