Washington (AFP) - Donald Trump's controversial senior adviser Steve Bannon will have a permanent seat at White House National Security Council (NSC) meetings, solidifying his role as one of the most powerful members of the president's inner circle.

In an executive memorandum signed on Saturday, Trump elevated Bannon, while downgrading the status of the Director of National Intelligence and the chairman of the Joint Chiefs of Staff on the security council's principals committee.

The DNI and Joint Chiefs chairman now will only be present at meetings "where issues pertaining to their responsibilities and expertise are to be discussed," the memorandum said.

Bannon, 63, credited in large part with successfully orchestrating the billionaire's upset presidential election victory, led the Breitbart News website described as a haven for the "alt-right" anti-mainstream movement.

The site ignited controversy during the presidential campaign because of its alleged alignment with white supremacists, white nationalists and anti-Semites.

White House spokesman Sean Spicer said in an interview Sunday with ABC television that Bannon was part of "an unbelievable group of folks that are part of the NSC."

"The president gets plenty of information from the chairman of the Joint Chiefs of Staff and gets briefed and what they've done is modernize the National Security Council, so it's less bureaucratic and more focused on providing the president with the intelligence he needs," Spicer said, explaining the shuffle.

Bannon, "is a former naval officer with a tremendous understanding of the world and the geopolitical landscape we have now," he said.

Spicer added: "Having the chief strategist for the president in those meetings who has a significant military background to help make, guide what the president's final analysis will be, is crucial."

Bannon had a blue-collar upbringing, but he quickly became part of the very establishment he rails against.

He began his career as a Goldman Sachs banker, then became a producer in Hollywood before taking over the Breitbart news platform. Bannon is currently on leave from Breitbart while working for Trump.