Caroline Flanagan will outline concerns about the cost of changes

Caroline Flanagan used the body's annual meeting to outline concerns about the cost of the changes.

Complaints are currently dealt with by the law society but an independent commission has been proposed.

It forms part of the Legal Profession and Legal Aid (Scotland) Bill, which is currently going through parliament.

The idea of an independent body has been welcomed, but there are fears that the price tag is prohibitive.

Concerns have also been raised that lawyers will decide not to carry out the type of work which is most likely to lead to complaints.

We have serious concerns over the mechanics of the commission Caroline Flanagan Law Society of Scotland

Mrs Flanagan told BBC Radio's Good Morning Scotland programme there were concerns about how the commission would operate.

"Whilst we welcome the fact that a commission will be set up we have serious concerns over the mechanics of the commission, how it will be funded, whether it's independent and whether it complies with human rights," she said.

Lawyers are also unhappy about the levy they would have to pay to fund the complaints commission.

Mrs Flanagan added: "The cost, we think, will be a lot more than the executive is stating and the cost will be borne disproportionately by high street solicitors, solicitors in small firms and rural practices."

Fee structure

Graeme Millar, chairman of the Scottish Consumer Council, said he supported the shake-up.

He said: "Any other professions have to pay a levy to be able to practice and get indemnity and everything else.

"That's appropriate and built in to the fee structure. We as consumers are the ones that pay for it anyway. If that's the cost of having a far better service then I think consumers would recognise it's money well spent."

Ministers have insisted the new quango will improve public confidence in the legal system.