Senator Brandis has come under fire over a contentious move to restrict his ministerial colleagues' ability to seek independent legal advice directly from the Solicitor-General, Justin Gleeson, SC.

Under changes made days before the federal election, no minister – including the prime minister – can seek advice from Mr Gleeson "except with the consent of the Attorney-General".

Legal experts have expressed concern the change is a power grab that restricts the independence of the Solicitor-General and reflects an irreparable breakdown in the relationship between the men.

But Senator Brandis has said the change is an "attempt, inspired by a request from the Solicitor-General himself, to regularise the practice" of Mr Gleeson receiving briefs from government and "it's not an attempt to exert any more control".

The two men are now at loggerheads after Mr Gleeson, the government's top legal adviser, released documents under freedom of information laws casting doubt on Senator Brandis' claims in Parliament he was consulted about the move.

A spokesman for Senator Brandis said: "The Attorney-General's statement to Parliament was accurate."

The documents, published by legal website Justinian on Tuesday, suggest Mr Gleeson was caught by surprise about the change.

In a letter dated May 4, Senator Brandis wrote to Mr Gleeson attaching a "final copy" of a revised guidance note on briefing the Solicitor-General, saying it had been prepared "having regard ... to your suggestions" at a meeting on November 30 last year.

However, Senator Brandis also added he had changed an instrument called the legal services direction, and both changes would "take effect immediately".

This gave binding legal effect to the move to stop ministers, departments and agencies briefing the Solicitor-General directly without the approval of the Attorney-General.

Mr Gleeson's notes from the November 30 meeting do not suggest the change was raised.

In a written decision explaining his reasons for releasing the documents to Justinian, Mr Gleeson notes this new direction "is the first time the process for briefing the solicitor general has been placed on a legislative basis" and it differs from the previous procedure.

A senior legal source told Fairfax Media the move was "a major compromise of the role of the Solicitor-General" and appeared designed to keep Senator Brandis "in the power loop".

"No cabinet minister can seek legal advice without the Attorney-General knowing about it and framing the way the question is posed," the source said.

Mr Gleeson is expected to appear before a Senate inquiry in early October, set up by Labor with the support of the crossbench, to probe whether Senator Brandis misled Parliament.

Shadow Attorney-General Mark Dreyfus said the change was "a breach of 100 years of convention about the way in which the Solicitor-General provides advice".

He said it appeared Senator Brandis had misled Parliament and he called on him to "fully explain all his dealings with the Solicitor-General".

Stuart Clark, the president of the Law Council of Australia, said it was "critical that legal advice which goes to government ministers and their agencies is frank, fearless and independent".

"Maintaining the independence of that office ensures executive decision-making is conducted within the confines of the law and the powers conferred upon the executive by the Parliament," Mr Clark said.