Rupert Murdoch reportedly instructed his editors to "kill Whitlam" before the fall of the Labor government in 1975.
Fairfax says the News Corporation chief's directive regarding former Labor leader Gough Whitlam is revealed in a diplomatic report from the US dated 1975.
The telegram from the US Consul-General in Melbourne, Robert Brand, reported to the state Department that "Rupert Murdoch has issued (a) confidential instruction to editors of newspapers he controls to 'Kill Whitlam'".
Mr Brand makes it clear that the words "kill Whitlam" were used in a political context and not as a physical threat, Fairfax says.
Mr Brand noted that Mr Murdoch had previously supported Mr Whitlam's election but his publishing empire turned against the leader.
"If Murdoch attack directed against Whitlam personally this could presage hard times for Prime Minister; but if against Labor government would be dire news for party," the telegraph reportedly said.
The directive came ten months before Whitlam's dismissal by the Governor General.
Comment was being sought from News Corp Australia.