A Somali-born author and vocal critic of conservative Islam, Ayaan Hirsi Ali, has cancelled her tour of Australia and New Zealand amid security concerns.

Hirsi Ali was scheduled to appear on the ABC's panel programme on Monday (3 April) before starting her tour, titled "Hero of Heresy". The tour was expected to begin in Brisbane on Thursday, before taking her to Melbourne, Sydney and Auckland.

Other panel members, who were due to appear with her on the Australian TV, were 2006 Nobel Peace Prize winner Professor Muhammad Yunus and former Denmark prime minister Helle Thorning.

The organiser of the trip, Think Inc, confirmed the news and said the cancellation was due to "a number of reasons including security concerns, and she hopes to be able to return to Australia in the not too distant future".

About 2000 tickets of Ali's speaking events were sold in Australia, but the organiser's said it will process refunds within 7 to 21 days.

Born to a Muslim family in Somalia, the 47-year-old Hirsi has been a vocal critic of Islam after renouncing her religion. She sought political asylum in the Netherlands in 1992, and was elected as an MP in 2003.

The former Dutch MP rose to international attention in 2004 as a writer of a controversial film, named Submission, which depicted violence against Muslim women. Due to the controversial subject of the film, her collaborator, filmmaker Theo van Gogh, was murdered by a radical Islamist.

Hirsi has also received several death threats over her defiance to Islam's treatment of women, and she has to live under 24-hour police protection.

Meanwhile, at least 400 people had signed an online petition opposing Ali's visit to Australia and New Zealand.

"Against a backdrop of increasing global Islamophobia, Hirsi-Ali's divisive rhetoric simply serves to increase hostility and hatred towards Muslims," the petition said.

People had also planned to hold protests at places where she was due to speak, the BBC reported.