Oliver Peterson: Australian correspondent on Peter Costello resigning as Nine Entertainment chair following alleged assault - Heather du Plessis-Allan Drive

Former federal treasurer and Nine Entertainment chair Peter Costello has resigned after he was accused of assaulting a journalist at Canberra airport.

Costello was accused of pushing a News Corp journalist after he refused to answer questions about the embattled media company.

Australian correspondent Oliver Peterson says Costello has denied the assault and claimed the journalist fell over.

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