Most trade associations offer consumers inadequate protection, according to a report published today.

People believe the associations - membership of which is usually shown by a logo - ensure companies and workmen adhere to a strict code of conduct and will offer a certain standard of service.

But an investigation by the watchdog Consumer Association's magazine Which? revealed that few of the 36 bodies it studied met all the requirements that it believed were crucial.

These standards include vetting tradespeople thoroughly before allowing them to join, carrying out continuous checks on its members and measuring how well they dealt with complaints.

The research also revealed the public's confusion about the large number of associations, with many people not knowing the difference between real associations and ones made up by Which? for the study.

Deputy editor Jon Dunning said: "The problem is a lot of people see a logo and assume it means the guarantee of a certain level of service and a code of conduct.

"But we should not assume that just because it has a logo that it is worth anything.

"In our research we did not find many organisations we were completely happy with.

"Some had good policies, such as on vetting members, carrying out ongoing checks or having adequate insurance cover, but hardly any met all our criteria.

"It is tricky for consumers to work out whether the association has a meaningful code of conduct without doing in-depth research as we have.

"There are two new schemes which should help consumers in the future. One is the Office of Fair Trading's Approved Code and the other is the Department of Trade and Industry's Quality Mark Scheme.

"These are both standards which associations must meet in order to be accredited by them."

The research also revealed people did not know the difference between genuine and made-up trade associations.

The Federation of Master Builders was recognised by 31 per cent of those questioned. But the National Federation of Roofing Contractors scored only six per cent, which was seven per cent less than the fictional Society of Registered Builders.