The United Nations says Australia violated an Iranian cleric's right to family life when he was booted out five years ago following adverse security assessments.
The Geneva-based UN Human Rights Committee said Sheikh Mansour Leghaei, 52, had to leave Australia after 16 years because he was considered a threat to national security, although he was never told why.
Mr Leghaei's wife and Australian-born daughter Fatima, then 14, left for Iran with him in June 2010.
His twin sons, Australian citizens and then aged 26, and his 20-year-old son stayed in Australia.
Australia's visa refusal, which compelled the family to choose whether to accompany him or stay in Australia, was an interference in the Leghaeis' right to family life, the human rights committee said in a statement.
"Furthermore, Australia did not give Mr Leghaei an adequate and objective justification for disrupting his long-settled family life," it said.
In its submission to the committee, Australia argued that the decision to expel Mr Leghaei was reached in accordance with Australian law and was in keeping with the International Covenant on Civil and Political Rights.
The committee says Australia should provide compensation.
The Australian government has 180 days to say how it will provide redress.
