A young Sydney man knew he had coronavirus when he turned up to work at a building site this week.
Police Commissioner Mick Fuller has said the serious breach was realised when officers visited his home this morning to find he was not there.
"That sort of behaviour is exactly why we need strong health orders, law enforcement and defence, getting the highest level of compliance," Commissioner Fuller said.
LIVE UPDATES: Premier begs for people not to attend protests
"One person could spread the virus.
"This guy knew he was positive."
Commissioner Fuller said more than 2000 compliance checks have been conducted to ensure infected people and their close contacts are not out-and-about in Sydney.
Of the 170 cases detected in the 24 hours to 8pm last night in NSW, at least 42 were infectious in the community.
Police are expecting more protests over the weekend.
READ MORE: Delta outbreak in NSW spreads as 170 new cases announced
Commissioner Fuller said "up to 1000 police" will be on hand to deal with the protesters.
"Coming into town to protest is not the answer," he said.
"If you think you can splinter from that and protest somewhere else in Greater Sydney, that force will be mobile and will be waiting for you.
"You have been given plenty of warnings."
READ MORE: Police 'will be waiting' for protesters planning on attending Sydney rally
