These AFP officers are tasked with trawling through the unspeakable. The base. The plain evil. Images and footages of children being sexually abused, tortured - killed even. Horrendous abuse made for the gratification of a pathetic army of sick voyeurs across the world who access the material via a computer or mobile phone.

The officers are looking for clues to capture offenders; identify and rescue the child, helping other law enforcement agencies across Australia and the world. There are limits on how long they can watch the images. There are separate rooms they can retreat to, to stop and refocus. They have psychological checks every six months.They work in groups or pairs, never alone. It is a difficult, difficult job.

But they are passionate about stopping the abuse.

One AFP Child Exploitation Assessment Centre member said about coping with the work: "One thing that resonates with me, which was advice from another colleague when I started here, was that you can't change what has happened to the victim in the past but we can work on changing their future".

And the abuse they see is unspeakable, yes. But child exploitation is an issue that needs to be spoken about. Desperately. Often and loudly.

That's the view of AFP Commander Lesa Gale who recently delivered a powerful speech in Ireland to the World Congress on Children's Rights and Family Law on the "global realities of child exploitation". The AFP was invited to talk and chose the subject, wanting to shine a light on the darkest of crimes.

As Gale, a Canberra mother-of-two with a 30-year policing career rose to speak before an audience in Dublin of 650 academics, judges, advocates, NGO representatives, she felt nervous. But determined. Very determined.

This was an officer who had investigated too many cases of sexual assault and child abuse. She had led the AFP's national and international online child exploitation investigations. She had seen more than enough horror.

Her speech didn't pull any punches.

The children who were being abused, mutilated and killed for an online audience were getting younger and younger - toddlers and even infants.

More abusive material was being "self-produced" by children thanks to technology such as webcams. Children, as young as four, were being tricked by online predators into producing sexually explicit images of themselves and uploading them to social media platforms.

In some impoverished countries including in Africa and Asia, live streaming of abuse was becoming more common. Buyers, sitting a world away, - including in Australia - could pay for live sexual abuse to be committed on a child - like renting a movie. They could pay a premium to "direct" the movie themselves.

Offenders were upping the ante to produce the worst material possible, and that could mean the death of a child.

"Unfortunately many of my colleagues working across the AFP child protection space have seen this for ourselves," Gale told the audience.

"Each day, our Assessment Centre receives imagery depicting infants being sexually abused .

"Officers are reporting a disturbing trend focussing on pain and death involving babies and toddlers. Producers of such material are trying to shock and go to the next level of violence, which has created an almost competitive environment.

"Innocent children are trading cards in these circles that have an insatiable appetite for such material.

"Last year, the AFP prosecuted an Australian man who was sentenced to 22 years imprisonment for soliciting the creation and birth of twin girls through a surrogate with the full intent of sexually abusing them.

"They were only 27 days old when the first sexual assault began."

That's just one heart-wrenching case among thousands.

Gale told the audience that every nine minutes, a webpage was opened somewhere showing a child being sexually abused. Of the 3.7 billion Internet users, at any moment, 750,000 of them will be child predators. A statistic she acknowledges is now a decade old.

"We expect it's a much, much higher number than this," she said.

Offenders are taking advantage of the fact that so many young people live their life online.

"The Australian Office of eSafety Commissioner recently released a report stating that on average, kids (aged 8 to 13) have two social media accounts and teens (aged 14 to 17) have three," Gale said.

"The most popular social media accounts for kids today are Youtube, Facebook, and Instagram. The majority of teens have these accounts as well as Snapchat.

"An alarming thought in relation to these statistics is that some of these teens could indeed be some of the 750,000-plus online child predators."

Gale says offenders target vulnerable children "who are often online unsupervised on what appear to be benign platforms". For example using an app that appears harmless but is in fact a way for an offender to make direct contact with a potential victim and convince them to meet up in the real world.

Offenders can also be guilty of sharing and sending abusive images.

"In the early and mid-2000s, in Australia the number of images seized when an offender was arrested was around 1000 images of a child being sexually abused. We were seizing kilobyte and megabytes of child exploitation material," Gale said in her speech.

"Today, on average a seizure is between 10,000 to 80,000 images and videos. Some seizures have contained more than one million multi-media files.

"We are seizing terabytes, petabytes of child exploitation material, cloud-based and hard drives. To put this into perspective, one petabyte is the equivalent of 20 million four-drawer filing cabinets filled with text."

Gale candidly conceded in her speech that an end to child exploitation was "beyond the capacity of law enforcement agencies alone".

They are up against poverty-stricken families who may trade their children and a lucrative marketplace willing to pay for the images. Gale says the United Nations in 2009 estimated that the production and distribution of child exploitation images generated between $3 billion and $20 billion a year.

Gale says the first step to ending the abuse is is ensuring child exploitation isn't a taboo subject.

"It isn't spoken about like weekend sport or terrorism, and it needs to be," she said.

"Our children are at risk, indeed sexually exploited, every minute of every day.

"By the time law enforcement is called in to remove a child from harm or bring an offender to justice, it's already too late. A child's life has been severely impacted, for life.

"More than any crime type, law enforcement agencies cannot arrest their way out of this problem."

Efforts are being made to register sex offenders and prevent their entry to child abuse hotspots such as Thailand, Indonesia and the Philippines.The most recent move by the Australian Government was to cancel the passports of the more than 16,000 people on the Australia's National Child Sex Offenders database.

Carly's Law, passed earlier this year, by the Australian Parliament, threatens 10 years' jail for online predators preparing or planning to cause harm to, procure, or engage in sexual activity with a child. That includes lying online about their age - in other words, pretending to be a child to lure victims in.

Gale says parents, schools, carers need to understand what their children are doing online and monitor them. And they need to contact police when they believe something is wrong.

The AFP helps facilitate the ThinkUKnow cyber safety education program to help those looking after children to realise the risks facing young people online.

"Know what your children are accessing through the internet," she said.

"You don't always know who you are speaking to on the other end. These predators are smart and they will use any means to exploit young people to get what they want.

"Make yourself aware of the risks; make yourself aware of how you can make the internet more secure for your children."

The AFP is focused on helping law enforcement agencies in poor countries, including in Asia, to reduce the vulnerability of children in desperate families.

The issue of child exploitation needs to be kept front and centre of decision-makers, Gale maintains.

"We need to ensure our governments are, and remain, genuinely committed to protecting children around the world from sexual exploitation," she said.

And what of those officers working day in day out in the AFP HQ? Gale says she is grateful to have such a dedicated team.

"It's all about protecting the kids and rescuing the children they do view in that material. That's certainly what drives that passion and commitment," she said.