A dramatic rise in the number of people being targeted by a relatively new crime known as 'sextortion' has seen thousands of British victims' lives turned upside down.

Four men have already killed themselves in the UK after becoming victims, with many of those being targeted children.

And while almost 900 people have already reported being ensnared by sextortion gangs so far in 2016, police believe the actual number of victims is far higher.

Also known as 'webcam blackmail', sextortion sees criminals use fake identities to dupe victims online and persuade them to perform sex acts in front of their webcam.

Perpetrators then threaten to send recorded videos of the acts to the victim's family or friends unless they hand over money.

Investigators in the UK say many victims are being targeted by organised criminal gangs from overseas – including in the Philippines, Ivory Coast and Morocco – making it much more difficult to stop.

New figures from the National Crime Agency (NCA) show there have been 864 reported cases in the UK so far this year, more than double the figure for the whole of 2015. In 2011 there were just nine reported cases.

Victims who reported crimes this year were aged between 14 and 82, with the highest proportion being men in their 20s. About 230 victims were under the age of 20.

But officers warned there is significant under-reporting of the issue due to victims feeling "ashamed or embarrassed", and that the actual number of sextortion cases is likely to be in the thousands.

This week the NCA and National Police Chiefs Council (NPCC) launched a new campaign giving tips on what those who have been, or are likely to be, targeted can do, using the slogan: "Don't panic, don't pay, don't communicate".

Don't panic – The police say they will take your case seriously, will deal with it in confidence and will not judge.

Don't pay – Many victims who have paid have continued to get more demands for higher amounts of money. In some cases, even when the demands have been met the offenders will still go on to post the videos.

Don't communicate further with the criminals. Take screen shots of all your communication. Suspend your Facebook account (but don't delete it) and use the online reporting process to report the matter to Skype, YouTube etc. to have any video blocked and to set up an alert in case the video resurfaces.

(Source: NCA)

This includes immediately contacting the police and their internet provider, and gathering evidence by taking screenshots of all communications.

Victims are also advised to temporarily suspend their Facebook account and use online reporting tools on YouTube and Skype to ensure any X-rated videos uploaded by the criminals are quickly blocked. They should never pay criminals and should cease all communication with them, police added.

Roy Sinclair, from the NCA's anti-kidnap and extortion unit, said: "Cases of webcam blackmail – or sextortion – are going up dramatically. As recently as 2012 we were only getting a handful of reports a year, now we're getting hundreds, and our law enforcement partners across Europe are reporting a similar picture."

The NCA and NPCC say webcam blackmail is a "relatively new and emerging crime" and that police are working with the Home Office to get a more accurate picture of the true scale.

Three victims – one teenage boy, a man in his 20s and another man in his 60s – give their accounts of how they became victims of sextortion. All were targeted after trying online dating.

Gary, in his late teens, from Hampshire: "I thought about suicide"

"I was working night shifts on my own. This meant I could not meet up with friends and had no social life. I was lonely so I tried going online to meet people. I would go online once an evening over the course of a few months. I went on different dating websites, wanting to get to know people on there. This made me happier. I felt better.

"One of the people I'd been talking to suggested I go onto Skype. I'd been talking to them for a while so I thought why not? They seemed persistent, which in hindsight was the first warning sign.

"At the time I was going with it. I was receiving quite a few messages, once a day or twice a day. She'd asked me for my Facebook profile and picture. The conversations had lasted a week or two, more than previous ones. It seemed normal.

"Then this woman started talking intimately. She invited me onto Skype where she looked similar to her profile picture. She was halfway across the room. It lasted for around 30 to 45 minutes, all on the phone. She said 'show me a bit more, and show me your face'.

"Then the messages came up – 'pay £500 or this is going all over Facebook. I want £500'. Then she started listing my friends' details. I said I could not afford £500, she said £200 was the lowest. I said I could only pay £50. I offered to go to the bank but went to the police station instead.

"I was trembling throughout the whole thing, shaking and thinking 'what's going to happen?' This will ruin my life and did not know what to do. If this video is released onto Facebook, what would I do? What's going to happen with my job? What will my friends think? I thought about suicide, it would have been too embarrassing. I would not have been able to face anyone.

"But I went to the police, and kept her talking by saying I was at the bank. Messages came through abusing me and saying 'I will keep doing it'. The police officers handled it well. They stopped and helped me through it. They made me feel better. I needed to talk to someone. Since then I've tried to put it to the back of my mind, and I've moved on with my life. There is always life afterwards. But I would not be here today if I had not spoken to anyone."

John, in his 60s, from Hertfordshire: "You feel destroyed"

"I'd been online using dating sites since I split up with my wife a few years ago. I had a friend who'd used a Filipino dating website so I thought I'd give it a try. Over time I made contact with a girl on there and we exchanged messages for about a week and a half, everything seemed to go really well.

"The kind of things we talked about were exactly those you would if you were beginning a relationship. I know now that they were very, very clever, getting to know me, getting to know my background, getting into my head.

"Then one night the girl suggested we move onto Skype so we could see each other. We exchanged some messages and she made some suggestion to say that she would remove her clothes if I did the same. I'd had a few glasses of wine so maybe my inhibitions had dropped a bit and I agreed.

"Straight away after that the threats began. They said "now I've recorded you. If you don't pay me I'll put that video all over Facebook and YouTube". My instant thought was I had no choice, and that I'd pay anything because I thought if they posted the video it would ruin my business and my family relationships.

"I transferred the money, but it was too late for them to collect it so I had to wait until the following morning to find out if they'd got it. They phoned me at 6am the next morning and told me that they'd deleted part of the video, but I had to pay them more or they'd post the rest of it. I paid them some more.

"I didn't go to the police straight away, I was too embarrassed. I was just a real mess and wanted to shut myself away, die in a corner somewhere, but after a day or so I went to the police station .

"Even now I have trouble going on to the internet and I can't use Facebook any more. I wake up every morning and what is always in my head is that I don't know if that video still exists or not. The police told me that people have committed suicide because of this, I can understand why. You feel destroyed."

Jimmy, in his 20s, from Northern Ireland: "She started sending me photos of my family from my Facebook contacts"

"I met her on a well-known dating app, and she suggested we move onto another app you can chat on. I got talking away to her for a few days. Then she suggested we exchange photos. Some of them got a bit sexy, y'know? She asked to see my Facebook profile, she wanted to make friends on there.

"Literally ten minutes after I'd sent her my profile I got this message: 'What would you do if I sent these photos to your friends and family?' I said to her 'No, don't do it'. And then I asked her what she wanted me to do.

"She said she wanted me to subscribe to these live webcam websites, some of them looked really dodgy, and she wanted me to send screenshots to prove I'd done it. She got angrier and angrier and then said 'Ok, give me money'. She wanted me to wire it to her, but when I went to the transfer shop it was closed. All the time she was messaging me every few minutes to check where I was. When the shop was closed she said she wanted me to send the money on Paypal.

"I said I didn't have enough money and started trying to bargain with her, but she started sending me photos of my family from my Facebook contacts, saying she would send the pictures to them. It was really stressful and I didn't know what to do. I caved in and sent her £150. She said she wanted £300 but I said no, deactivated my Facebook and went to the police.

"A week or so later after I'd gone back on Facebook I got this friend request from someone I didn't know. They said they were a big fan of mine and they'd seen my photos, which they were going to send to my family. I expect it was the same person again. I reported them to Facebook and got the profile removed.

"I was so worried about what my friends and family would think. I've spoken to my mum about it, that was tough enough, but I still can't talk to anyone else. I'm ok now, but at the time it was so hard, having to go into work and stuff and pretend like this wasn't happening. The police still call me just to check on me. They say some people who've been through this have a few tried to do something daft afterwards, but I'm ok now."