BUSINESS leader Hugh Morgan has called for dual citizenship to be outlawed, comparing it to having a mental illness.

In a speech at Deakin University last night, the prominent Liberal Party supporter and former Business Council chairman said a person with dual citizenship had "at least the beginning of a bipolar disorder".

Mr Morgan said citizenship was one of the most important elements of personal identity and would have a bearing on Australia's survival as a nation.

"I am convinced that if we took Australian citizenship seriously, we would not tolerate this bipolarity. If you are an Australian then that should be the end of the matter," he said.

"If your loyalties are to another country and Australian citizenship is merely a convenience, then you should hand in your Australian passport and feel content that your loyalties and your passport are in accord one with the other."

In a speech titled "Can Australia survive the 21st century?", Mr Morgan called for the word "rich" to be embraced as a positive, and called for immigration policy to be used to sustain Australian culture. Mr Morgan was giving the inaugural Wilfred Brookes Memorial Lecture, named after prime minister Alfred Deakin's grandson.

It comes amid an argument about what it means to be Australian. Treasurer Peter Costello in February singled out Muslims while calling for those who do not share Australian values to be stripped of citizenship. Prime Minister John Howard backed his stance.

Mr Morgan said Australians with dual citizenship had only qualified commitment to its future sovereignty and independence. "That is something that we in our strategic position cannot afford," he said.

He said most people would agree that national survival depended on wealth, population, social and political coherence and symbols of nationhood and citizenship.

Mr Morgan also weighed into the "culture wars", backing John Howard's criticism of the "dumbing down" of English teaching in Australian schools due to postmodernism and political correctness. He said post-modernism — which he defined as the belief that all versions of the truth were equally valid — threatened to cut the link between generations of Australians.

SANE Australia executive director Barbara Hocking said it was unfortunate that the speech could be seen to trivialise a serious mental illness.