A Melbourne man faces more than 100 charges after allegedly forcing young girls in Australia and overseas to send sexually explicit pictures of themselves to him by threatening to send explicit images of them to their families and schools.

Broadmeadows man Daniel Thomas Watson, 32, allegedly created large numbers of fake social media and email accounts to pose as a teenage girl or boy and allegedly lure the children into sending the material to him.

Details of the charges emerged in a prosecution summary of facts presented to the court.

Police allege Watson even forced some of his victims to pose in explicit pictures with their younger siblings and send the pictures to him.

According to the police summary of facts, some of Watson's alleged victims, who police believe number in the dozens, threatened to commit suicide if he did not stop demanding sexually explicit material, and threatening them with public humiliation if they did not comply.

It is also alleged Watson kept offending after he was first arrested in August 2013 and granted bail.

Watson faces more than 100 charges, including transmitting child pornography, causing a minor to be involved in the transmission of child pornography, using a carriage service to engage a person under 16 in sexual activity and causing a minor to be involved in the production of child pornography.

Watson was investigated by police after a 14-year-old girl and her mother contacted Victoria Police and said a teenage girl had been using threats to demand nude photos of the 14-year-old and her younger sister.

The 14-year-old said she had been communicating with the other girl via Facebook and an app called Kik.

The ABC cannot reveal the identities Watson allegedly used to pose as a teenage girl, as police say he sometimes used the real identities of other alleged victims to lure new girls into sending material to him.

The prosecution summary of facts states that when police traced the internet protocol address of the email linked to the social media accounts, it was held in the name of Watson's sister.

Man continued to contact, threaten victims after previous arrest

In August 2013, members of Victoria Police's online child exploitation taskforce, Astraea, executed a warrant at Watson's house, and seized computer equipment and a smart phone.

Watson denied knowledge of the girl who complained to police, and said the social media accounts were used by a number of other people.

It is alleged Watson then admitted to using some of the accounts, and said it was possible he had communicated with the complainant, but that he had a serious drinking problem and found it difficult to remember what he said or did online.

According to police, Watson then signed a consent form, allowing police to access Kik, Gmail, Facebook, Instagram and Hotmail accounts. What they allegedly found was a complex web of deceit, threats and traumatised young girls.

Police say that after Watson was arrested and bailed, he allegedly contacted one of the victims again and tried to force her to send him more sexually explicit pictures and video. Watson was charged with more offences and denied bail.

In the prosecution summary of facts, police detailed Watson's alleged modus operandi, which began with Watson allegedly posing as a teenage girl and contacting real young girls randomly and asking "if they wanted to have some fun".

It is alleged he would send them an explicit photo, which was usually of another, earlier victim, and then ask them to reciprocate, which many did.

"Demands and threats were persistent and they escalated, with the accused to publish any photos or videos the victim had provided on the internet, or give them to family, friends and school," the documents allege.

"On occasions he threatened to publish their home address with the material. In some instances the accused threatened that he would tell police that they were sending child pornography (since he was pretending to be a young teenager).

"In some instances the accused demanded that the victim give him the password to their social media and email accounts, which he then used to gather personal information to use against them and monitor them."

As the police investigation unfolded, they realised that alleged victims were not confined to Victoria, but lived interstate and overseas.

Watson also allegedly posed as a number of different people, to make victims think they were interacting with a group of friends. If victims became reluctant to send images, he would imply that his "crew" of friends would find and harm them.

The prosecution fact summary says some victims became so distressed at being threatened with publication of their images and videos that they threatened to commit suicide.

"Why are you doing this ... just tell me ... you can't do this ... it's not fair ... do you want me to kill myself is that what you want ... because I can," one 15-year-old Northern Territory girl wrote.

Watson allegedly replied: "Nope I want u to be my personal pic buddy ... I want u for life. Until I get sick of it ... I've kept our secrets this long."

Abuse left victim feeling 'powerless'

In a police interview a victim from New South Wales described the effect of Watson's alleged psychological manipulation of her.

"I felt powerless. I felt like ... I actually wanted to kill myself. That it got to the point that I wanted to kill myself because I didn't know what to do," she said.

It is also alleged Watson forced a 15-year-old from the United States to perform an explicit act with her five-year-old sister, then send him a video of the act. Watson then allegedly demanded more images, and threatened to report the victim to the police if she did not send them.

Watson allegedly repeated this with a 14-year-old Australian girl and her younger sister. It was the younger girl's birthday, and shortly after cutting her birthday cake, she told her mother what had happened. This ultimately led police to Watson.

Watson also allegedly forced his victims to hold up signs when they sent him nude pictures of themselves. Some of these signs related to football, including "Liverpool 5 MUFC 3 end of story" and "Liverpool FC Champions 2013/14".

He also allegedly forced another United States girl to hold up a sign: "I'm 12 and in da bad girls club", and "F**k me, I'm 12 years old".

He also allegedly forced some victims to hold up signs in which they named other victims, which he then sent as supposed proof that he was a teenage girl himself.

In total, 11 girls have made complaints to police about Watson, but the number of children he allegedly attempted to procure explicit images and videos from is much higher.

Watson was originally also charged with blackmail offences, but a magistrate ruled on Tuesday that those charges could not be proven beyond reasonable doubt, as the photos and videos Watson was sent could not be defined as "property".

The case is adjourned until March 25.