Enforcement agencies will start a nationwide inquiry into the sale of ordinary meat labelled as more expensive organic produce, after a growing number of reports of the practice.

Some butchers are believed to be cashing in on the higher value of organic meat, which sells for up to five times the price of that from a conventionally reared animal. The crime carries little risk because it is very difficult for shoppers to tell when they are being duped.

Some farmers are also believed to be selling meat as organic at farmers’ markets and food fairs when they are not certified to do so. Trading Standards officers will lead the investigation, which will also include sales of meat conducted over the internet.

Sales of organic food in Britain are rising by 12 per cent a year and are worth £1.2 billion annually. With sales of organic meat, home produced and imported, valued at more than £200 million, enforcement agencies said they were not surprised that rogue traders were seeking to move in on such a lucrative sector. A chicken worth £2 to £3 can fetch £10 or £11 with an organic label. Ordinary steak that sells for £10 to £15 per kg can fetch as much as £29.59 per kg if it is said to be organic.

The Food Standards Agency is funding the development of a test that can detect the amount of antibiotics in meat to identify if it is genuinely organic. Organic producers must follow strict rules that limit drug use in animals.

This test, developed by experts at the Central Science Laboratory, can be used by Trading Standards officers. At the moment they can investigate only by examining paperwork.

The Trading Standards Institute was alerted last year when two traders were fined for using organic labels on ordinary meat. Since then there have been reports of breaches from all round the country. David Pickering, of the institute, told The Times: "We have believed for some time that there are some strange things taking place in the organic food market. The problem is that when meat is sold unwrapped it is extremely difficult to see any physical differences between organic and conventional meat.

"We are now working out exactly how this area should be policed. It is obvious with such a fast-growing market that some people will be anxious to cash in with fake organic meat."

Evidence has also been collated by a television investigation. the ITV1 West Eye View: Porky Pies, which is to be shown in the South West tomorrow, identified a string of butchers in Gloucestershire, Dorset and Devon selling organic meat when they are not allowed to do so. Further checks found that the meat was not organic. A farmer was also found to be selling organic pork sausages at a market when he was not authorised to do so.

Rogue traders face fines of up to £5,000 per offence if they are found guilty of fraud.

One of the main problems is the lack of checks made on organic produce to check its authenticity. The questions over organic meat are particularly embarrassing for the Soil Association, the largest organic organisation, whose latest campaign to boost organic farming begins today. The association has almost 4,000 members, who produce 70 per cent of organic food grown in the UK, but just 4 per cent of land is used for organic produce.

Patrick Holden, director of the association, has ordered tougher controls to police organic produce. He wants to appoint a roving inspector to help Trading Standards officers to expose fraud, and also to introduce spot checks.

A campaign to recruit butchers to become authorised sellers of organic meat will also to be launched. The association will reduce its £400 fee to £250.

Robin Maynard, spokesman for the association, said people should report dubious traders to it or Trading Standards. "There are always people who put premium and profit before principle and philosophy."

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