Reece Kershaw.
© Gary Ramage
Australian Federal Police Commissioner Reece Kershaw.
A global child exploitation sting triggered by a US Department of Homeland Security investigation has rescued four Australian children as young as two months old who were used to produce and ­exchange child rape videos and images through online pedophile networks around the world.

In one of the largest joint operations in the country — led by the Australian Federal Police and spread across five states — 16 ­people have been charged with 728 child exploitation and sexual abuse ­offences following a two-year ­investigation into the online ­exchange of child pornography.

The arrests come as AFP Commissioner Reece Kershaw warned of a spike in traffic across the so-called dark web — ­including live-streaming and incidents of child sexual abuse and child grooming — since the outbreak of the coronavirus, prompting a call for parents to strictly monitor their children's online activity during the lockdown.

The Australian understands that the four children were aged between two months and eight years and are believed to be ­related to those who had sexually abused them and then exchanged the graphic images through highly encrypted web forums.

Three were rescued in NSW and the fourth in Victoria in a joint operation, codenamed Walwa, involving the AFP, state and territory police and Joint Anti-Child Exploitation Teams.

The 16 people were arrested and charged with contact offending and producing and exchanging child sex material through the internet.

Three are from NSW, one in South Australia, five in Queensland, three from Victoria and four from Western Australia. Of the 728 charges laid, 632 were against those caught in Victoria and 70 against those in NSW.

While the vast majority of live-streaming of child sexual exploitation originates in known hotspots including The Philippines, the latest case reveals ­material is also being generated in Australia and channelled through exchange networks via the dark web.

"This type of offending has no borders," Mr Kershaw told The Australian. He said the depth of depravity would be hard for most people to comprehend.

"It is very hard to explain to a society, to people who don't see the images ... these involve images like you've never seen before," he said.

"If I had my way I'd set the dark web on fire."

The two-year investigation was prompted by a US Homeland Security covert operation into ­encrypted dark nets that operate through virtually untraceable networks on the web and cannot be accessed without specific software, making it difficult for law enforcement agencies to hunt down offenders.

Homeland Security officers in Phoenix, Arizona, had uncovered activity in Australia and channelled the intelligence to the AFP through the Australian Centre to Counter Child Exploitation, which was set up in 2018 as part of global investigations into the rise in dark web child exploitation.

Mr Kershaw said there had been a spike in activity since the strict COVID-19 social-distancing restrictions were put in place around the world, adding that the dark web had recently become "congested".

Home Affairs Minister Peter Dutton said the establishment of the ACCCE had proven its success through the arrests and the rescue of Australian children from harm.

However, he said he was concerned about the rise in users across the internet accessing the material since the outbreak of COVID-19.

"We have had increasing ­reports of people seeking to exploit the increased amount of screen time children will be spending online during the current climate to gain access to and abuse children," Mr Dutton told The Australian.

"The work of the ACCCE and Australian law enforcement does not stop. The ACCCE continues to drive the fight against online child exploitation, despite the challenges faced by Australia as a ­result of COVID-19," he said.

"As these outcomes demonstrate, we will continue to pursue all those who commit these horrific crimes, which can have a terrible impact on survivors, their families and the Australian community at large."

Mr Kershaw said all parents, guardians and carers needed to be extra vigilant in the current environment to ensure that children were not being exposed to these ruthless predators.

"More and more kids are being subjected to predatory behaviour by these sick perverts. We are very concerned about that," he said.

"Some of these people are very good at exploiting children ... so we are urging all parents to be ­connected to their kids when they are on line."

The arrests come as law enforcement agencies claim they are being hampered in their efforts to track offenders through the dark web because tech companies have been reluctant to co-operate in ­allowing access to encryption codes for the purpose of criminal investigations into child exploitation.

Mr Dutton has warned the big digital platforms such as Facebook and Google, as well as device manufacturers including Apple and Samsung, that more legislation will be considered if greater co-­operation is not forthcoming.

At a Press Club address earlier this year, Mr Kershaw said that while 10 years ago there would have been 300 referrals a year for online child exploitation activity, that figure had now ballooned to almost 20,000.

"In the US, it's in the millions," he said. "And understand that each referral is not a single file — it could be thousands, millions of videos and pictures of children being sexually abused.

"The Australian Centre to Counter Child Exploitation is dealing with a database of 22 million seized videos and images, and it will soon merge with a Queensland database of another 50 million," Mr Kershaw said.

"We are seeing more videos, younger children, and more violence. We are seeing the rape and torture of our children. All for ­sexual gratification."

He said investigations in relation to Operation Walwa were still ongoing, both in Australia and internationally, with officers from the ACCCE and local police analysing reams of seized material to try to track down any more child victims in Australia.