Bannon, the former head of Breitbart News, appeared before the House intelligence committee on Tuesday.
"This was unprecedented in all the interviews that we have done".
He added if Bannon was refusing to answer certain questions, then it's reasonable for his lawyer to have coordinated with the White House on the "scope" of executive privilege.
Former White House chief strategist Steve Bannon's attorney relayed questions, in real time, to the White House during a House Intelligence Committee interview on Tuesday, The Associated Press reported.
He is the ranking Democrat on the committee condemned what he called 'a gag order from the White House'. "So we served him with a subpoena during the hearing to convert it from a voluntary appearance to a mandatory one".
The House intelligence committee is conducting one of the two main congressional investigations of the Russian Federation issue, but they been hampered by partisan bickering.
"The separation of powers allowed Trump to invoke executive privilege when Bannon met with congressional investigators but Mueller is part of the same executive branch as the president so it won't apply when Bannon sits down with the special prosecutor".
"Steve Bannon has nothing to do with me or my presidency", Trump said after the book's publication. Bannon refused to answers questions, provoking a subpoena from the panel's Republican chairman.
Burck did not immediately respond to CNBC's request for comment.
The developments brought to the forefront questions about White House efforts to control what current and former aides tell Congress about their time in Mr Trump's inner circle, and whether Republicans on Capitol Hill would force the issue. CNN reported Wednesday that Bannon had stuck a deal with the special counsel to submit to an informal interview in place of testifying.
That comment appeared in "Fire and Fury", Michael Wolff's book about the first year of the Trump presidency.
In comments recounted in Wolff's book Fire and Fury: Inside the Trump White House, Bannon, who served as the Trump campaign's chief executive officer, said he did not expect to be a witness in Mueller's probe into potential collusion between Russian Federation and the Trump's inner circle.
Mueller's been investigating Russian meddling in the 2016 presidential election for months.
Underscoring the break, Mr Trump said Mr Bannon had "lost his mind" and branded him "Sloppy Steve" via Twitter. That means he can tell Mueller what he knows behind closed doors - and without having to testify in front of a grand jury for now.
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