Sixteen people across five states have been charged with more than 700 child exploitation offences after a two-year investigation involving Australian authorities and US Homeland Security Investigators.

Starting in 2018, matters were regularly referred to Australian authorities by US officials following their investigations into an online website where users paid to access child abuse material.

Australian investigators ultimately executed 18 search warrants and arrested 16 people across NSW, Victoria, Queensland, South Australia and Western Australia on 738 charges.

Queensland Police shared footage of one of the arrests. (Queensland Police)

Authorities were also able to remove four Australian children from harm, three in NSW and one in Victoria.

Queensland Detective Superintendent Denzil Clark from the Child Abuse and Sexual Crimes Group said strong law enforcement partnerships and a whole-of-community response are crucial to protect children from online predators.

"Queensland Police will continue sharing our expertise and working collaboratively with our national, interstate and international counterparts to target those who pose a risk to children in our community," Detective Superintendent Clark said.

"Every day Argos investigators are online monitoring a range of platforms targeting predators who are attempting to exploit children.

"But the first defence in the global fight against online child exploitation is parents and carers, who we ask to be vigilant with electronic devices used by their children and monitor their children's online activities."

The man is one of 16 Australians arrested in the joint investigation. (Queensland Police)

Those charged are expected to appear in court in the coming months.

Just weeks ago AFP Commissioner Reece Kershaw warned of a spike in traffic across the dark web — including live-streaming and incidents of child sexual abuse and child grooming — since the COVID-19 outbreak, prompting calls for parents to strictly monitor their children's online activity.

Homeland Security Australian attache Adam Parks said the arrests came at a critical time.

"More so than ever, children are increasingly online for their schooling, to socialise with their friends and family, and to play games," he said.

"Let this be a warning that law enforcement is undeterred by COVID-19 and remains on-duty to keep our children safe in Australia, the US and online."