By Rory Cellan-Jones
Business correspondent, BBC News
Nine in every 10 butchers claiming to be selling organic meat may be breaking the law, BBC News has learned.
Butchers who cut up meat or make sausages have to be certified
The Soil Association is warning that butchers must apply for certification before advertising meat as organic.
Organic produce sales are booming - but consumers may find it hard to work out which products are genuinely organic.
There are no reliable lab tests to show if a product is organic, so consumer confidence depends on regulation by bodies like the Soil Association.
All food sold as organic must come from growers or processors who are registered and inspected by an approved certification body - the Soil Association is one of 10 such bodies.
Butchers who cut up meat or make sausages count as processors, so they have to be certified even if they buy their meat from an organic producer.
Soil Association inspection director Steve Belton said: "Without certification, they're breaking the law if they're doing anything other than selling pre-packed meat."
BBC News contacted all the certification bodies and discovered that across the UK only 63 butchers had gone through certification - and in London there were just two.
BBC News talked to a number of butchers in the capital who described their meat as "organic".
Some said they did not know about the certification process, others claimed it was too expensive and bureaucratic.
In one shop in Richmond in Surrey, BBC News bought some "organic" sausages, then asked the butcher whether he had been through certification.
He showed BBC News the paperwork apparently proving that the meat had come from organic farms, but admitted that his own shop had not been certified.
"I'm going through certification right now," he added, claiming his wife had put the form in the post.
But the Soil Association told us they had not received an application.
Officials there say it costs only £500 to go through certification and they are introducing a cheaper deal for butchers.
Trading Standards officers fear there is a wider problem for consumers.
As farmers' markets spread across the country, stalls selling "organic" produce may not be what they seem.
Spot checks by Michael Eade, an environmental health officer for Richmond Council in Surrey, found stall-holders were often unaware of the rules on certification.
He has been telling those who label their products organic they need to be able to prove it.
Pre-packaged food should carry a code number and the logo of an organic certification body, and those selling loose produce should have a certificate.
Mr Eade said: "Ask the trader to show you the certificate - many are proud to display it as a marketing tool."
He has launched prosecutions against some traders who have broken the rules, but that is unusual.
"I don't think this borough is unique," he says.
"The problem is widespread and other enforcement bodies should be looking into it."