Yohann Ramchelawon hid his identity behind a photograph of a teenage boy he grabbed from the internet to groom his victims using bogus profiles on social media sites.
The Mauritian national used Instagram, WhatsApp, Skype and Facebook to spark conversations with girls aged between 12 and 17 from across the world.
WATCH: The Express & Star spoke to one of his victims and her father
But he quickly steered the chats towards intimate subjects and requested naked images of his victims, while using a profile picture of a boy aged around 16 who police said 'can only be described as looking like a young Justin Bieber'.
The 30-year-old also coerced them into performing sex acts in front of webcams after Ramchelawon and threatened to share the images they had provided with friends and family if they did not meet his demands.
Dc Kerry Haywood from West Midlands Police’s Public Protection Unit, said: “He used various aliases including Ryan Smith and ‘Santiago’ and claimed to be a teenager who was sending messages during school or college lessons.
“He sent poems, would call them ‘baby’ and tell them he loved them after chatting online for little more than a day.
“However, he quickly steered the chats to intimate subjects and persuaded them to take their clothes off − and he then used these naked images to blackmail them into sending more explicit pictures and videos.
WATCH: Police react to the sentence
“The enquiry started when a girl from Manchester reported to police that a boy named Ryan was asking for intimate images. The investigation soon snowballed and we identified many more victims and online conversations with girls in different countries.
“I’d like to thank that 12-year-old girl for breaking her silence and putting her faith in the police. It’s helped us put a calculating sex predator behind bars and undoubtedly protected other girls for falling into his trap."
Judge John Wait said: "I'm satisfied from your conduct that you have a perverted sexual attraction to very young girls.
"The consequence of your conduct has been awful and you present a significant risk of serious harm of further offending unless restrained. You are a dangerous offender and need to be sentenced as such."
Ramchelawon, who was on bail for similar offences at the time, was caught after West Midlands Police tracked the phone that he used to message a 12-year-old Manchester girl to a house in Walsall, where he was living at the time.
The youngster told the Express & Star that she felt 'disgusted' with herself when she found out the truth.
Detectives eventually caught him at a house in Victoria Lane, Huddersfield, where he was arrested on March 6.
Hundreds of indecent images were found on his digital devices as officers uncovered victims from Coventry and Walsall, plus Lanark in Scotland, Liverpool, St Ives, Shoreham-by-sea and East Ham, Stafford Crown Court heard.
But examination of his computer and phone revealed he had contacted girls living in New Zealand, Brazil, UAE and Russia.
Ramchelawon − who gave his home address as Walls Street, Halifax, when arrested − denied two counts of inciting a 12-year-old girl to engage in sex acts online, eight charges of possessing indecent images of children, and two of distributing the images.
He also denied another sex assault, and a sexual assault against a six-year-old Coventry girl in October last year.
But midway through his trial at Wolverhampton Crown Court he entered a guilty pleas to all offences.
This afternoon, he was jailed for 15 years and must serve at least 10 years behind bars before being allowed to apply for release.
Once released he will serve the rest of his sentence on licence. Once his normal licence period has ended, he will be subject to a further five years on licence. He will be subject to recall to prison if he breaches any of the terms of his release.
He was also ordered to sign the sexual offenders register for life.