News Corp co-chairman Lachlan Murdoch has invoked his grandfather's reporting of Gallipoli to lash the Abbott government's new national security laws that could jail journalists for up to 10 years.

Mr Murdoch said Australia's press freedom was under threat and had already fallen dramatically by world standards.

Lachlan Murdoch arrives with Sarah at the annual Keith Murdoch Oration at the State Library of Victoria. Credit:Darrian Traynor

"It might surprise you that today Australia ranks 33rd, just behind Belize, on the Freedom house index. 20 years ago we ranked 9th," Mr Murdoch said during the Keith Murdoch Oration at the State Library in Melbourne on Thursday night.

Mr Murdoch said the government was frequently asking Australians to trust them 'we're from the government', when attempting to censor the media.