Nine Entertainment chairman Peter Costello has rebuffed suggestions he struck a journalist who was questioning him over alleged culture issues at the Australian media company.

Costello has rejected accusations of hitting the questioner after video emerged of the incident.

Liam Mendes, a reporter for the Australian, had attempted to question Costello at Canberra Airport on Thursday over allegations of harassment at Nine.

Costello is adamant he did not assault the journalist.

“I walked past him, he walked back into an advertising placard and he fell over,” he told reporters later on Thursday.

“I did not strike him.

“If he’s upset about that, I’m sorry, but I did not strike him.”

In a video published by the Australian, Mendes follows Costello through the airport as he asks about Nine chief executive Mike Sneesby.

Costello appears to walk towards the reporter at one point before Mendes falls backwards.

“You have just assaulted me,” the journalist says in the video.

No complaint has been lodged with police over the incident.

The Nine boss was appointed in 2016 after a career in politics where he served as the federal treasurer under Liberal Prime Minister John Howard.

Asked about the incident, Education Minister Jason Clare said it was a matter for the police but said everyone should be safe at work.

“My view is that if a journalist asks you a question, you stop and answer it,” he told Seven’s Sunrise programme on Friday.

“That’s the simplest way to do it, rather than run away or say ‘no comment’ or accidentally knock somebody over.”

Opposition Leader Peter Dutton said he hoped the journalist was okay.

“Peter’s been a friend of mine for over 20 years and I’ve never seen any active aggression from him,” he told Nine’s Today show.

“There are obviously other camera angles, which I haven’t seen.

“But the Peter Costello I know is somebody who doesn’t have an aggressive bone of that nature in his body.”