The Federation of Small Businesses has attacked the government’s measures to combat cowboy builders, calling its proposals “anti-competitive” and likely to aid rogue traders working in the black economy.

In a letter to construction minister Nick Raynsford, FSB construction adviser David Brown said the government’s proposals for clamping down on rogue traders were “totally impractical” for small businesses.

Brown was particularly critical of the government’s proposed quality mark scheme.

The letter said: “It would not be practical to produce a ‘quality mark’ for this type of work. The work is so varied that the skills required can only be obtained by experience. To attempt to set standards and then supervise them would not be possible, or if it was, cost effective.”

The letter continued: “The bulk of this work is carried out by individuals or small businesses with less than 10 employees. In these instances, the management structure will centre around one man. Accreditation would not be practical.”

Brown added that the provision of a single approved list of contractors would also be impractical, as it would have to cover about 700 000 companies and would need to be upgraded on a daily basis.

A spokesman added: “Any licence to trade has inherent problems and we are against it. CORGI has been a disaster for both customers and businesses and this scheme will fare no better.”