One in five UK teenagers admits to buying a false ID card over the internet, while another one in five teenagers under the legal age have bought knives.

The headline statistics come from a national survey of 1,200 16 to 18 year olds, commissioned by software solution provider Clarity Commerce.

Underage teenagers use the ID cards to get into cinemas (12 per cent) and tattoo studios (six per cent). The cards look genuine, and busy retailers are easily fooled by them.

The survey results deal a blow to government attempts to combat teenage crime, underpinned by last week's launch of the Proof of Age Standards Scheme (PASS) in London. PASS is the UK’s national guarantee scheme for proof-of-age cards.

Clarity Commerce's Michel de Beer, responsible for EMEA retail business, said: "While the government's efforts are well intentioned, the survey results show that ID schemes have had their day as they do not offer enough support and protection to businesses."

Currently only foreign nationals are legally required to carry the cards, but the government is targeting young people as most likely to use the cards to prove their identity.

Big UK retail stores such as Tesco, Asda and Marks & Spencer have instructed staff to ask customers who look under 25 for ID before selling them alcohol and cigarettes. Although this offers some protection, retailers could be losing significant revenue from customers legally entitled to buy goods, but being prevented from doing so through lack of appropriate ID.