Labor wrote to Mr Turnbull late on Sunday seeking his assurance the opinion of Solicitor-General Justin Gleeson, SC, was sought on the bill, which the government had hoped to pass through Parliament before the end of the year.

Mr Gleeson is locked in a public brawl with Attorney-General George Brandis over a legally binding directive Senator Brandis issued before the July 2 election, which prevents ministers seeking Mr Gleeson's advice without the written approval of the Attorney-General.

Legal experts have expressed concern the directive may result in the Solicitor-General, who provides independent advice, being "frozen out" of advising the government and allow the Attorney-General to "shop around" for opinions regarded as politically convenient.

Shadow attorney-general Mark Dreyfus said in the letter to Mr Turnbull that he considered it of "great importance to know whether Mr Gleeson has been offered the opportunity to advise on this bill".

"If he has not, I request the reasons why, and whose advice has been sought in his place," he said.

Mr Dreyfus said the bill "seeks to make changes to Australian law in relation to suspected terrorists that are without precedent in our country, or indeed in the developed world" and submissions to a parliamentary committee had "raised doubts about its constitutionality".

At an explosive Senate inquiry on Friday, Mr Gleeson said the government did not ask him to advise last year on significant revisions to a contentious proposal to strip terrorists of Australian citizenship.

Senator Brandis subsequently told a parliamentary committee Mr Gleeson had advised there was a "good chance" the bill would survive a High Court challenge.

Mr Gleeson said his advice was "taken out of context" and the bill introduced to Parliament "was a different bill to the one I advised upon".

Senator Brandis told the inquiry the citizenship bill had a "very long and vexed" political history and "this was not my bill".

He said Mr Gleeson was, "in substance", advising Immigration and Border Protection Minister Peter Dutton.

Mr Dreyfus said he was writing to Mr Turnbull to "ensure this same situation is avoided for the current bill under consideration".

The bill will allow the Attorney-General to apply to the Supreme Court for an order that a convicted terrorist posing an "unacceptable risk" of committing serious offences be detained beyond their sentence.

The Parliamentary Joint Committee on Intelligence and Security will report on the bill by November 4.

"Given the current breakdown in relations caused by Senator Brandis's disgraceful treatment of Mr Gleeson, this committee can no longer assume that he has been included in the drafting of this significant bill," Mr Dreyfus said.

Senator Brandis has defended the new direction about the briefing of Mr Gleeson as "administrative housekeeping" that is consistent with the law and historical practice.

But Mr Gleeson has said it effects a "radical" change to the way his independent office functions.

He said on Friday he considered the direction was unlawful and he would make a "conscientious decision" to flout it if approached directly by the Prime Minister or others for advice.

Fairfax Media has previously revealed Senator Brandis sought advice from private barristers on issues ranging from the same-sex marriage plebiscite to proroguing Parliament rather than relying on advice from Mr Gleeson.

Without commenting on specific cases, Senator Brandis told the Senate inquiry on Friday "it is perfectly appropriate in a proper case to seek advice from the private bar" and Mr Dreyfus had done the same in office.