The bill proposes a shake-up of aspects of the legal profession

In a written submission to the Justice 2 Committee, the Faculty of Advocates said reforming the complaints handling system was "unjustified".

The Law Society of Scotland, which will also address MSPs examining the bill, said the reforms could fall foul of human rights legislation.

The executive said a consultation found that 85% of people supported reform.

Proposals for the committee have been included in the Legal Profession and Legal Aid (Scotland) Bill.

It lacks an appeal system, which is quite a fundamental point Douglas Mill Law Society of Scotland chief executive

There will be no appeal against its decisions and the committee will be appointed by the executive, which the Law Society claimed could infringe human rights.

The Faculty of Advocates also called into question the executive's ability to remove commissioners it considered 'unsuitable'.

It said the executive's involvement in appointments would compromise the new committee's credibility and independence.

Roy Martin QC, dean of the faculty, said: "The proposed legislation is an unjustified intrusion by the state into the independence of the legal profession which will not improve the interests of those who need access to justice.

"Self regulation is recognised throughout Europe as one of the prime guarantees of the independence of the legal profession and the executive's current proposals will only add unnecessary bureaucracy, duplication and expense."

'Robust and transparent'

Mr Martin said the faculty already operated a "robust and transparent" complaints handling system.

He said he was not aware of any accusations that the faculty had deliberately favoured the position of an advocate when a complaint was made.

The Law Society said that complaints about the services offered by its 11,000 members should be handled independently.

But chief executive Douglas Mill said there were real concerns about the way the Scottish Executive wants to achieve that.

The society has expressed concerns about the proposals

He said: "Our concern is that under the European Convention on Human Rights legislation, the bill creates a body that is too close to government, it's not independent of government.

"It also lacks an appeal system, which is quite a fundamental point both for solicitors and equally, in fact perhaps even more so, for the public."

The new committee would cost about five times the current system and solicitors would have to pay for the cost of investigating complaints against them, even if they were shown not to have been at fault.

Some claim that increasing the costs of providing their services will mean they take on fewer cases, while some may decline to take on the sort of cases where complaints might arise, such as conveyancing and family disputes.