A committee of MPs called on Tuesday for the political and legal roles performed by the Attorney General to be split, saying the government's reform proposals did not go far enough in restoring public confidence.

The job of the Attorney General, the government's top lawyer, has been called into question following a number of high profile cases where critics said the dual role of minister and legal adviser had come into conflict.

The advice given by former Attorney General Lord Goldsmith on the legality of the Iraq war and the decision to order the Serious Fraud Office to end its probe into an arms deal between BAE Systems and Saudi Arabia led to calls for an overhaul.

Goldsmith also faced controversy over the police cash-for-honours inquiry when declined to step aside from any involvement even though he could have been in the position of deciding whether any Downing Street aides should face prosecution.

However, the Justice Committee said the government's draft constitutional reform bill would not provide greater accountability.

"The draft bill fails to achieve the purpose given to constitutional reform by the Prime Minister," the committee's report said, adding it would actually give greater power to the government while failing to add to transparency.

"The main problem with maintaining public confidence in the office of the Attorney General arises from combining the functions of legal adviser with ministerial functions.

"We believe that transparency requires separating the political functions of the Attorney General from the legal functions."

The report also said that the Attorney General, currently Baroness Scotland, should also not have the right to end Serious Fraud Office investigations.