Of 264 people who had complained, only six saw any action taken against their doctor, and 82% were unhappy with the fairness of the procedures.

And 85% said they were left with a more negative impression of the council by the end of their case.

However, participants in the study selected themselves by responding to newspaper advertisements calling for people who had complained to the GMC to come forward.

Increased complaints

The number of complaints against doctors has trebled over the past five years, with 3,000 complaints arriving at the GMC in 1998.

Yet 88% of these cases never made it to a hearing, and despite the GMC's attempts to generate a more public-friendly image, more than half the respondents said they were not confident they knew how to proceed after contacting the council.

The CA recommended the GMC increased the number of non-medical members and that it provide improved information about how complaints progressed and where they could get help with their case.

Charlotte Gann, editor of the CA's Health Which? magazine, said: "Anyone who has experienced a problem with a doctor should be able to make a complaint without feeling intimidated.

"They should be confident that their complaint will receive a fair and thorough investigation by an open and impartial body whose procedures are easy to access, transparent and clear.

"The fact that so many people we spoke to didn't feel this happened is serious cause for concern and reflects badly on the GMC."

Improvements

However, the GMC had responded well to the association's recommendations, and had already implemented some of the measures.

"We are pleased the GMC is committed to change - but it is going to have to work hard if it is to convince the public that it's working to protect the interests of patients, not of doctors," Ms Gann said.

The GMC is overhauling its current complaints procedure, which involves complaints being screened before they investigated.

In the survey, 59% of the cases that passed this hurdle resulted in no action being taken.

In those that did, 58% of complainants were dissatisfied with their experience, and one woman said her doctor got off with a "slap on the wrist".

Actions

GMC cases are investigated by one of two committees - one that deals with conduct and one that looks at performance.

The most common action the committees took was a formal warning - as in 29% of cases - although the council has the power to suspend a doctor's right to practise indefinitely.

A GMC spokeswoman said: "We have been aware that our standards of service have not always been as helpful as they might have been in the past and that is why we have been taking steps to address this.