IRANIANS have overtaken Afghans to become the largest group of asylum seekers arriving by boat to Australia, and have been labelled ''troublemakers'' by immigration officials who are unhappy that they are unable to send home those who fail refugee status.

Iranian boat arrivals leapt eightfold, from 197 in 2009-10, to 1549 last year. At the same time, visa success rates have plummeted, from 100 per cent in 2008, to 27 per cent last year.

Iranian asylum seekers are middle class, well-educated, secular or Christian, with good English. Credit:James Brickwood

Unlike Afghans fleeing villages, the Iranian asylum seekers are middle-class, well-educated, secular or Christian, with good English. It is exactly these vocal, motivated, urban Iranians who have been forced to flee an Islamic regime that views even teachers as ''political'' if they raise human rights objections, community leaders say.

But immigration officials take a different view, accusing recently arrived Iranians who had received initial rejections for refugee status of being agitators in the Christmas Island and Villawood riots. ''Contumacious behaviour, wilful disobedience,'' Immigration Department secretary Andrew Metcalfe told a parliamentary inquiry.