Peter Costello has resigned as chair of Nine Entertainment, days after being accused of bumping into a journalist at Canberra's airport.
The media company's newspapers reported the former treasurer's departure on Sunday, with current deputy chair Catherine West stepping into the main role.
Mr Costello tangled with The Australian reporter Liam Mendes at Canberra Airport on Thursday, with video appearing to show him knocking over the journalist after being confronted with questions about harassment allegations at Nine.
The former Liberal treasurer has denied assaulting the journalist and said Mr Mendes tripped over an advertising placard, and was not pushed over.
Nine's board was already set to meet on Friday before the incident, but its agenda was updated to include the incident involving Mr Costello.
"I thank the board for their support over the last decade and particularly during the events of the last few weeks," Mr Costello said in a statement.
"There are enormous challenges ahead but I believe Nine is the best placed Australian media company to weather them and prosper."
In a video published by The Australian, Mendes follows Mr Costello through the airport as he asks about Nine chief executive Mike Sneesby.
But he denied striking the reporter later on Thursday.
"I walked past him, he walked back into an advertising placard and he fell over," Mr Costello said.
"I did not strike him ... if he's upset about that, I'm sorry, but I did not strike him."
Mr Costello appears to walk towards the reporter at one point before the journalist falls backwards.
"You have just assaulted me," Mendes says in the video.
Nine has been embroiled in scandal across the last few weeks, dealing with sexual harassment allegations within the organisation.
Labor Treasurer Jim Chalmers criticised Mr Costello over his treatment of Mr Mendes.
He did not offer him assistance after he was knocked over.
"It's really important that we treat journalists with respect, that journalists are safe in their workplace," Dr Chalmers said.
"And if anyone should know that, it should be the chairman of a major media organisation."
Ms West thanked the outgoing chairman for his "dedication and commitment" to the company.
"As chairman, he has always put the needs of the company first and his decision to stand down and pass on the baton of leading Nine at this time is in line with that approach."
Mr Costello had been chairman since 2016.
