Four men have committed suicide after being targeted in a new, fast-growing sex blackmail scam.
Victims are being lured into exposing themselves or committing sex acts by women online after accepting their friendship requests on social networking sites.
They then face payment demands of hundreds of pounds - or threats that recordings of their behaviour will be sent to family and friends whose contact details they have unwittingly given access to.
Daniel Perry, from Dunfermline, 17, took his own life after threats to reveal his compromising online conversations.
Police would not reveal details of the other suicides, but said they were within the past year and added there could be more.
Martin Hewitt, of the National Police Chiefs' Council, said: "We started to see it emerging about 18 months ago.
"Last year we had about 300 offences recorded in the UK and we're now this year over 900, and I suspect there's a significant number that don't get reported because the crime is preying on people's embarrassment and their humiliation of being caught out doing something like this."
Organised crime groups in the Philippines, Morocco and Ivory Coast were discovered running many of the sextortion scams, some using British girls.
Most of the UK victims are men aged 18-24, the eldest was 82 and the youngest 14. Some women have also been targeted.
Police have issued advice to victims, urging them not to pay or panic, but to shut down their social media accounts and report what has happened.
Schoolboy Ronan Hughes, also 17, was tricked into sending intimate photographs of himself, then faced a demand for £3,000 to avoid exposure.
Mr Hughes from Clonoe in County Tyrone died in June of last year. His parents said he took his own life.
A man in Romania recently appeared in court over the incident, charged with producing and distributing indecent images of children.
The investigation has seen PSNI liaising with a number of agencies in a variety of jurisdictions - including Policia Româna, the Directorate for Investigating Organised Crime and Terrorism in Romania, the National Crime Agency and Europol.
PSNI Detective Superintendent Gary Reid said the investigation has been “complex and protracted and we are grateful to our colleagues in our partner agencies for their assistance to date”.
“Detectives from the PSNI are currently in Romania assisting our colleagues with this phase of the investigation,” he said.
“As legal proceedings are now ongoing, it would be inappropriate to comment further at this stage.
He reminded internet users to be mindful of their online activity “particularly with strangers”.
Roy Sinclair, from the National Crime Agency's (NCA) anti-kidnap and extortion unit in the UK, said: "There is huge under-reporting of these kinds of offences, often because victims feel ashamed or embarrassed, but of course criminals are relying on that reaction in order to succeed.
"This is why we are launching this new campaign. We want victims and potential victims to know how they can protect themselves and to understand what to do if they are targeted.
"This is still a relatively new and emerging crime type, so the NCA and police are working with the Home Office to get a more accurate picture of the true scale."