The world's largest media company, News Corporation, is threatening to deny coverage of movies starring artists who routinely refuse to give interviews to its outlets, one of its senior journalists has revealed.

The different arms of News Corp are working together to ''push back'' against the publicists to movie stars who are blocking media access to their charges, said News Ltd's entertainment editor-at-large, Rebekah Devlin.

Rupert Murdoch and his wife, Wendi, at the Academy Awards.

''They are very quickly becoming the most powerful people in the world,'' Devlin told the Caxtons advertising conference. ''More and more actors have it in their contract that they don't want to do publicity for a film. So how are you going to get access to the likes of Katherine Heigl if she's doing a film but refusing to do interviews.''

She said the News Corp chairman, Rupert Murdoch, or ''Uncle Rupe'' as she called him, was involved in drawing up a strategy of how to deal with what she said was a ''big challenge'' for media organisations. It is not known whether the issue will be on Mr Murdoch's agenda when he arrives in Australia this week for his annual visit.