AUSTRALIAN political leaders have slammed the Australian War Memorial's top historian Peter Stanley over his claim Japanese plans to invade Australia in 1942 were a "myth".

Both Prime Minister John Howard and Opposition Leader Kim Beazley flatly rejected Dr Stanley's argument yesterday.

The historian has angered veterans' groups with his claim that Australia perpetuated the myth through a "pathetic" desire to exaggerate the nation's role in the war.

Marking Battle-for-Australia day at the war memorial yesterday, Mr Howard said in early 1942 the Australian mainland and the security and freedom of its people were "directly" threatened.

"I pay a special honour to those men and women who participated in the Battle for Australia, whether as members of the services or as civilians, all played a crucial role in repelling the attack," he said.

Mr Howard described Dr Stanley's views of Japanese activity, including 100 air raids from Broome to Townsville and the midget submarine attack on Sydney Harbour, as "insubstantial".

Mr Beazley was even more blunt saying Japanese invasion plans were still active into 1943.

He said Dr Stanley's paper was "offensive and wrong".

"There is no basis for saying that invasion was not a serious option," Mr Beazley said.