Tony Abbott has accused Paul Keating of verballing Prince Charles by claiming the future king of the United Kingdom thinks Australia should ditch the monarchy.
Just days before Prince Charles arrives in Australia to open the Commonwealth Games, Keating said: "I have no doubt he believes Australia should be free of the British monarchy and that it should make its own way in the world."
Keating, who as Labor Prime Minister advocated for a republic, added: "Why would he or anyone of his family want to visit Australia pretending to be, or representing its aspirations as, its head of state?"
The comments from an opinion piece published in London's Sunday Times have angered former Liberal Prime Minister Abbott.
"Prince Charles would just want to do his duty and he shouldn't be verballed by an ex-PM," the now-backbencher posted on Twitter.
Another senior right-wing Liberal, Eric Abetz, also rounded on Keating, accusing him of mounting "self-serving and egotistical" arguments for a republic.
"Mr Keating's musings clearly have no basis in fact and are just a sad feature of the latest Republican push," the Tasmanian senator said.
"Along with wanting to change the flag, Mr Keating regularly finds new ways to try and push for a republic despite the Australian people rejecting his own model."
Prince Charles and the Queen have repeatedly stressed it's up to Australians to decide whether to follow the republic path.
Keating also said Prince Charles was a hard-working, enlightened and conviction-driven person who would always be welcome in Australia as the crown prince or as monarch of Great Britain.
"But the pretence of representing this country and all that it stands for is something he and we could well do without."
Prince Charles and his wife Camilla, the Duchess of Cornwall, will be officially welcomed at a reception in Brisbane on Wednesday, before opening the Commonwealth Games on the Gold Coast in the evening.