Moment Channel Nine chairman Peter Costello appears to push over a reporter after confronting him at the airport

Nine Network chairman Peter Costello has been filmed pushing over a journalist after being approached at an airport.

Mr Costello, the former federal treasurer in the Howard government, was questioned by The Australian journalist Liam Mendes after arriving at Canberra airport on Thursday afternoon.

The 66-year-old declined to answer a series of questions regarding a $1 million payout to the channel’s former news boss Darren Wick, who is facing sexual harassment allegations.

Mr. Mendes introduced himself to Mr. Costello and questioned why the Nine’s boss had not expressed his support for the network’s CEO, Mike Sneesby.

Mr Sneesby has come under fire following reports that he approved the large payout to Mr Wick.

Just a minute after Mr. Mendes started firing questions, he appeared to be pushed to the ground by Mr. Costello.

Nine chairman Peter Costello (pictured in the video) was filmed pushing over a journalist at Canberra Airport on Thursday

Costello, 66, was questioned by Australian journalist Liam Mendes (pictured) after arriving at Canberra Airport on Thursday afternoon.

GoPro footage captured the moment Mr Costello crashed into Mr Mendes, knocking him to the ground.

Mr Costello appeared to laugh before leaving the nervous Mr Mendes to pick himself up.

The apparently frustrated reporter continued to follow Mr Costello into the airport car park and accused him of ‘assault’.

“Mr. Costello, you can’t do that, you can’t do that, it’s all caught on camera,” Mr. Mendes said.

‘That was quite violent behaviour, Mr Costello. Journalists who work for Nine approach people this way every day and you attacked me at that very moment,” he claimed.

‘These are serious questions, Mr Costello. You can’t just push someone.

“Is that behavior appropriate for a working journalist?”

Outside Parliament House on Thursday evening, Costello denied pressuring the journalist.

“There is no assault,” Costello said.

“I didn’t lay a finger, fist or anything on him.”

Mr Costello said Mr Mendes was walking backwards during filming and tripped over a billboard.

“I’ve seen it happen a million times…reporters back into the posts and fall over,” he said.

“I didn’t hit him.”

Mr Costello also denied that viewers of the footage would describe him as aggressive.

Before appearing to push Mr Mendes, Mr Costello had asked the chairman of the Nine: ‘Do you support Mr Sneesby as CEO and his handling of the Darren Wick saga?’

Mr Wick, the former head of Nine News, was the subject of serious allegations of misconduct shortly before his resignation from the company in March.

It is understood that both Mr Costello and Mr Sneesby were aware of the allegations at the time of Mr Wick’s resignation.

Mr Sneesby has since faced criticism for approving Mr Wick’s $1 million financial settlement, which included a payout and leave entitlements.

It is understood Mr Costello was only aware of the payout after Mr Sneesby approved it and has not publicly supported the CEO since.

Mr Costello signed a letter to all nine employees last Thursday, obtained by the ABCwhich acknowledged the ‘serious’ claims against Mr Wick.

The journalist had introduced himself to Costello (pictured) and began to wonder why the Nine boss had not expressed his support for the network’s CEO Mike Sneesby.

“We recognize that we need to do more,” the letter read.

All nine employees must complete updated sexual harassment prevention training by June 30.

It is understood Mr Costello was in Canberra on Thursday for the opening of Nine’s new office in Parliament House.