President-elect Donald Trump has reportedly offered retired Lt Gen Michael Flynn the position of national security advisor, according to a top official in Trump's transition team. It is unclear if the 54-year-old registered Democrat has accepted the position.

Flynn, who was sacked as head of the Defense Intelligence Agency in 2014 by President Barack Obama, has advised Trump throughout his campaign and could potentially oversee a staff of about 400 people should he take the role. The Washington Post reported that Obama allegedly fired Flynn over his leadership style.

According to The Los Angeles Times, the position does not require Senate confirmation and is based in the White House. As Trump's national security advisor, Flynn would be tasked with guiding a president with no national security experience through complex global issues.

Flynn would give Trump advice on how to deal with the battle against the Islamic State (Isis), China's expansion efforts in the South China Sea or an international health crisis. He would also serve as a point of contact with a number of agencies, including the State Department and the Pentagon.

"This is a guy who has the president's trust, has credentials with the military, credentials with the intelligence community and credibility with Congress," Republican Representative Devin Nunes of California told The Washington Post. Nunes, who is chairman of the House Intelligence Committee and member of Trump's transition team, added: "He's a very serious person. He takes his job very seriously."

However, Flynn has had some controversial moments since leaving the federal government. The New York Times reported Flynn has blamed the Islamic faith for the issues in the Middle East and is known to repeatedly use the phrase "radical Islamic terrorism". Flynn also reportedly once posted a video on Twitter that included the phrase "Fear of Muslims is rational."

Flynn surprised former colleagues when he visited Moscow last year and appeared next to Russian President Vladimir Putin at a gala for the Kremlin-run propaganda channel RT. The retired general admitted he was paid but defended the trip, according to The Washington Post.

His refusal to denounce Trump's support of the use of waterboarding and other torture techniques to interrogate suspected terrorists has led to condemnation by civil rights groups.

"Michael Flynn has exhibited basic contempt for international law, including the Geneva Conventions and laws prohibiting torture," John Sifton, the deputy Washington director of Human Rights Watch, told the Post. "By nomination Flynn, President-elect Trump will be cementing a dark return to the illegalities of the Bush administration and further undermining the foundation of the international human rights system."

Over a week after being elected president, Trump has only officially appointed two people to his upcoming administration. Trump tapped RNC Chairman Reince Priebus as White House chief of staff and Steve Bannon, head of alt-right publication Breitbart News, as chief strategist. The president-elect has not announced any other cabinet positions.