The Queen could lose sovereignty over Australia if Scotland becomes independent, according to a senior solicitor.
David Denton SC, a senior counsel and adjunct professor of law at Victoria University in Melbourne, has urged constitutional monarchists and republicans to "renew the debate on Australia's future constitutional framework with some urgency" as "an independent Scotland may yet create an Australian republic".
Scottish First Minister Alex Salmond has pledged to retain the Queen as head of state of an independent Scotland.
But Mr Denton believes Scottish independence could create "an Australian constitutional vacuum" if the United Kingdom that existed when the Australian federation was agreed in 1900 ceases to exist.
Writing in Melbourne-based newspaper The Herald Sun, he said: "The UK itself is the sovereign state under international law. It was under this single UK that we Australians agreed to federate in 1900 under our constitution.
"The Australian constitution is unequivocal in that it united the Australian people under the crown of the United Kingdom of Great Britain and (now) Northern Ireland."
He said any alteration in the law touching the succession to the throne "requires the assent of the parliament of Australia".
He added: "If the Parliament in Westminster wishes to pass legislation to facilitate a matter touching on the succession to the crown of a new-fashioned UK (as it must inevitably become) then the parliament of Australia must give its consent to this as it will affect the law of Australia, not the least of which is our constitution and our states.
"The United Kingdom (that) Australians agreed to federate under will no longer exist. A UK which is de jure separated is not the UK for Australian constitutional purposes.
"It is possible to envisage an Australian constitutional vacuum existing if our UK ceases to exist.
"Whatever is to happen, it seems that it is no longer a matter for Australians to simply await a re-agitation of the republic debate after the passing of the reign of Queen Elizabeth.
"She may shortly not even be Queen of the United Kingdom of Great Britain and Northern Ireland nor, therefore, the Queen of Australia."