A plot to bomb Melbourne's Queen Victoria Market, foiled by a British family, never posed any credible terror threat, police say.
The tourist hot spot was on Tuesday revealed as one of multiple targets of a man who claimed to be part of an overseas terrorist network.
Over a five-month period he sent encrypted texts and voice files to members of the family, who acted as willing participants in the scheme, with instructions on how to detonate a bomb at the market, the Herald Sun reported.
But the 'recruit' was actually a family of "amateur jihadi hunters" and the correspondence was forwarded to Australia's Federal and Victorian police.
Assistant Commissioner Ross Guenther on Tuesday said the threat was assessed as not credible and there was no need for concern.
"There is no current threat to the Queen Victoria Market, Federation Square, St Paul's Cathedral or any other location in Melbourne or more broadly, across this state, at this time," he said.
Mr Guenther said early this year, police learned of communications between a person probably in Pakistan and a person in London posing as an extremist.
The man believed to be in Pakistan is known by police to be an ISIS supporter and a serious threat.
The plot apparently involved making a car bomb and driving it at a crowded corner of the market.
"That person did provide instructional advice to person in the UK, believing them to be living in Melbourne," Mr Guenther said.
"The information was ultimately shared with our law enforcement security partners who assess that information and concluded it posed no credible threat to Victoria."
Mr Guenther said Australia has been a target of ISIS and its affiliates and such communications are not uncommon among jihadi networks.
Police regularly receive similar threats and they are assessed based on risk.
"If the threats become extreme they go into our joint arrangements with the AFP and ASIO," Mr Guenther said.
More than 200 people in Victoria are being monitored for terrorism risk but police recommended against members of the public "jihadi hunting".
"It's a very unsafe practice to engage with person overseas, because for a start, we don't understand their capacity to promote and actually commit such an act," the senior officer said.
Queen Victoria Market chairman Paul Guerra said police told him of the plot on Monday and his people are working closely with investigators.
Premier Daniel Andrews said a "probable" threat level is in place for Australia but in this instance, the threat was not credible.
"That is not to, in any way, diminish the seriousness with which we take these issues ... We are vigilant and we work very closely with our international and our national partners."