A Scottish Sun investigation today exposes the shocking new craze which is putting thousands of people at risk of infection. Ruthless cowboys flout strict health laws to rake in a fortune by tattooing kids with dodgy equipment at the boozy underground bashes. And the horrifying trend comes just as the number of Scots diagnosed with deadly blood disease Hepatitis C has soared. Last night one expert warned: "If this is allowed to continue there will be an epidemic of people with deadly infections."

Tat parties, where groups of friends hire a tattooist to turn up at one of their homes, have become massively popular in Scotland. It is illegal for anyone to work as a travelling freelance artist without the correct licence. Tough health rules mean it is also illegal to tattoo anyone under 18 - even with parental consent. But we can reveal that just two months ago, two 12-year-old girls had tattoos etched on their FACES at a party in Shettleston, Glasgow. Last night a friend of the family said: "Their parents had no idea they were going to this party and when they came back with tattoos they went absolutely nuts.

"But it's almost impossible to track down the tattooist because these things are all done through the internet or word of mouth. "These two kids are now left with tattoos they might not be able to hide - it's madness."Web-based tattoo artists rarely have proper training and often carry out work on filthy kitchen tables and dirty carpets at parties. Greedy Barry Tunstead, 28, is one of the growing number coining it in from illegal tattoo parties he advertises on the internet. The dad-of-one, who works from a top-floor flat in the city's Govan area, says on his advert: "I am available for tattoo parties any size. I'm based in Glasgow but travel all over the country."

When contacted by undercover reporters, Tunstead - who also uses the name Ryan Hope in emails - directed our reporter to a Bebo page called Tattoo Gathering. And he bragged he had "no problem" breaking the law by tattooing a 17-year-old girl. He said: "I would need consent from your friend's parents due to the age but I've no problem doing the tattoo. "My prices are very reasonable. There's no set fee, it's pay as you're tattooed. I worked in a top studio in Glasgow for a year but the chair rental kept going up so decided to freelance."Leading tattoo artists last night slammed the cowboys prepared to break the law for a quick buck.

Frank McNab, who has run an officially licensed studio in Glasgow for almost 20 years, said: "Parties are now a major problem in Scotland and the implications are horrendous. "It's all about the cash - they can do maybe 15 people a night at a party and charge anything from £10-£50 a tattoo. It's pure profit. "They don't care about the strict hygiene measures we have to stick to - they could be carrying out work on someone sitting at a dirty table with a dog running about and drink and drugs everywhere. "I get up to 25 people a week coming into the studio asking me if I can help fix a problem with a dodgy tattoo they have had done at a party - everything from scarring and nerve damage to problems with the ink colour running."

Frank, below, added: "Because I run a licensed studio I have to maintain hygiene standards higher than a doctor's surgery. "These cowboys are buying equipment and ink off the internet for £200 and setting up in business. "You wouldn't go to someone's house to have a tooth removed, so it's insanity to go there to get a tattoo done. "I've heard about the two 12-year-olds, and I was also told of a woman in Glasgow contracting Hepatitis C because a guy at a party used a dirty needle to tattoo her. "The bubble's going to burst soon if this is allowed to continue and there will be an epidemic of people with deadly infections."

A Scottish Government spokeswoman said: "Licensed tattoo artists are governed by strict rules, which state that tattooing and skin piercing can be carried out in locations other than a dedicated studio. "The legislation doesn't rule out working in a private home. "Licences are issued by local authorities and it is their responsibility to enforce licensing rules. "If an artist is working across more than one council area he or she must be licensed by each council. "We would always advise anyone to use a licensed artist."Glasgow City Council confirmed it has NOT issued any licenses allowing people to travel to clients' homes to carry out tattoo work.

And health officials last night warned of the dangers of tat parties after seeing an increase in reported Hep-C patients.

Health Protection Scotland said 567 Hep-C cases were diagnosed between April and June this year - compared to 371 for the same period in 2008 and 525 last year. HPS epidemiologist Kirsty Roy revealed that campaigns warning of the dangers of the blood infection had boosted the number of people being diagnosed.

She said: "The problem with Hep-C is that people may not know for many years that they have been infected so sometimes have difficulty in pinpointing when it could have occurred."But she added: "The rise in tattoo parties is quite concerning, especially if the tattoos are not being done following the appropriate guidelines and ink and needles are being shared.

"If you are going to have a tattoo done make sure you use a reputable licensed artist."Last night Tunstead denied he'd arranged tattoo parties - and denied that he used the alias Ryan Hope. He said: "I run a Bebo page that lets people show off their tattoos, but it has more than 100 members and if Ryan Hope is one of them I have never heard of him."