A One Nation candidate has posted and backed conspiracy theories about the September 11 terror attacks on his Facebook page.

John Cox, who is running for Redcliffe in the upcoming Queensland election, questioned if footage from the 2001 terror attacks that killed nearly 3,000 people was legitimate on social media.

Mr Cox shared a video called, 'Where is the plane that flew into the second tower on 9/11' from a conspiracy news page in December, Buzzfeed reports.

One Nation's John Cox questioned the legitimacy of the 9/11 attacks on his Facebook (pictured)

'I wish the news was always neat and straight,' he wrote under it.

Claiming to be a 'rare' news broadcast it allegedly shows the moment the second tower of the World Trade Centre exploded without a plane flying into it.

The conspiracy theory claims the attacks were an actually an inside job and the plane flying into the building was added later digitally into news footage that was later broadcast.

John Cox is One Nation's candidate in the upcoming Queensland election

'The oppressed need to wake up to the lies being told by the mainstream media and the attacks were 'pure murder by [the] American government,' was just one comment made on the video.

Cox also shared a video that claims the crash of hijacked American Airlines Flight 77 into the Pentagon was also faked.

'There is no evidence of a plane having crashed anywhere near the pentagon,' the reporter in the video says.

'The only pieces left that you can see are small enough that you could pick up in your hand… there are no large tail sections, wing sections, a fuselage, nothing like that.'

Cox agreed with the video's conspiracy theory that no plane crashed into the Pentagon.

'Honestly, where are the engines, where are the wheels, the fragments are so small you can pick them up in your hand, the world needs honesty,' Cox wrote.

He is running in Redcliffe, north of Brisbane, against Labor Attorney-General Yvette D'Ath.