Virgin boss Sir Richard Branson said a conman posing as Defence Secretary Sir Michael Fallon attempted to dupe him out of $5 million (£3.8m) after lying about a kidnapping.
The 67-year-old spoke to a man who "sounded exactly like Sir Michael" who said a British diplomat was being held hostage by terrorists and here was a "very sensitive reason" for wanting to get him back.
Writing about the incident on his website, Sir Richard said his assistant had received a note on what appeared to be official notepaper with a request to call the Defence Secretary.
He said: "He told me that British laws prevented the Government from paying out ransoms, which he normally completely concurred with. But he said on this occasion there was a particular, very sensitive, reason why they had to get this diplomat back.
"So they were extremely confidentially asking a syndicate of British businesspersons to step in.
"I was asked to contribute $5 million dollars of the ransom money, which he assured me the British Government would find a way of paying back."
Sir Richard said he was "sympathetic" to the request, but wanted to carry out checks.
After he rang Downing Street and asked to be put through to Sir Michael's office, he realised the truth.
He wrote: "His secretary assured me that Sir Michael hadn't spoken to me and that nobody had been kidnapped. It was clearly a scam. I told them what had happened and we passed the matter over to the police."
The tycoon also wrote of a similar incident where a fraudster impersonated him and was able to con $2 million (£1.5m) of money meant to help victims of Hurricane Irma in the British Virgin Islands.
He wrote: "They told me that they had received an email from somebody claiming they were my assistant, to arrange a call with me.
"When the call happened the conman did an extremely accurate impression of me and spun a big lie about urgently needing a loan while I was trying to mobilise aid in the BVI.
"They claimed I couldn't get hold of my bank in the UK because I didn't have any communications going to Europe and I'd only just managed to make a satellite call to the businessman in America. The business person, incredibly graciously, gave $2 million, which promptly disappeared."
He added: "People used to raid banks and trains for smaller amounts - it's frightening to think how easy it is becoming to pull off these crimes for larger amounts."
Victims of scams and fraud
Victims of scams and fraud
Susan Tollefsen, Britain's oldest first time mother, was scammed out of £160,000 by a fraudster she met on an online dating site. A man claiming to be an Italian gold and diamond dealer told her he was in the middle of a land deal but couldn't access cash. Tollefsen felt sorry for him and started wiring him money, eventually selling her jewellery, her flat and borrowing £32,000 from friends to give him. Read the full story here.
In March 2015 an American woman who was only identified as 'Sarah' went on the popular US television programme the Dr Phil Show to reveal she had sent $1.4 million to a man that she had never met. Although she was certain she wasn't being scammed, her cousin made her go on the programme because she was convinced it was a scam. Find out more about the story here.
Maggie Surridge employed Lee Slocombe to lay a £350 deck in her garden in March 2015. However Slocombe used a combination of lies to scam Surridge out of thousands of pounds. He told Surridge that the front and back walls were dangerous and needed rebuilding and also conned her into building a porch, all for the cost of £8,500. Read the full story here.
It's not just individuals who can be the victims of scams, big corporations can also fall foul of these fraudulent practices. In 2015 Claire Dunleavy repeatedly used a 7p 'reduced' sticker to get significant amounts of money off her shopping at an Asda store in Burslem, ending up with her paying just £15.66 for a shop that should have cost £69.02. Read the full story here.
Sylvia Kneller, 76, was conned out of £200,000 over the space of 56 years thanks to scam mail. The pensioner became addicted to responding to the fraudsters, convinced that she would one day win a fortune. Ms Kneller would receive letters claiming she had won large sums of money but she needed to send processing fees to claim her prize. Learn about the full story here.
Leslie Jubb, 103, became Britain's oldest scam victim in August last year when he was conned out of £60,000 after being sent an endless stream of catalogues promising prizes in return for purchasing overpriced goods. The extent of this con was discovered when Mr Jubb temporarily moved into a care home and his family discovered what he had lost. Find out more about this story here.
Stephen Cox won more than £100,000 on the National Lottery in 2003 but has been left with nothing after falling victim to two conmen. The 63-year-old was pressured into handing over £60,000 to the men who told him his roof needed fixing. They walked him into banks and building societies persuading him to part with £80,000 of cash while doing no work in return. See the full story here.
Last year the Metropolitan Police released CCTV footage of a woman who had £250 stolen at a cash machine in Dagenham. The scam involved two men distracting the woman at the machine, pressing the button for £250 then taking the money and running away. Read about the full story here.
Rebecca Ferguson shot to fame as a runner up on the X-Factor in 2010 but fell victim to a scam artist last year when someone she had believed to be a friend conned her out of £43,000. Rachel Taylor befriended the singer in 2012 and claimed to be a qualified accountant, so Ferguson allowed her to look after her finances. Instead of doing this Taylor stole £43,000 from the Liverpudlian singer. Read more here.
When Rebecca Lewis discovered her fiance had started a relationship with a woman he met online she packed her bags to leave. But that didn't stop her checking out the mystery woman, Rebecca quickly realised Paul Rusher's new love was actually part of a romance scam. She told Paul just before he sent the scammers £2,000 which was supposed to bring his new girlfriend to England. Find the full story here.