Controversial speaker and vocal critic of Islam Ayaan Hirsi Ali has cancelled at the last minute her speaking tour of Australia and New Zealand, citing security concerns.

Ali was due to appear as a panellist on the ABC's Q&A program tonight, but has also cancelled.

Her Hero of Heresy tour was due to begin in Brisbane on Thursday, before taking her to Melbourne, Sydney and Auckland.

Ali said in a statement she regretted that, "for a number of reasons including security concerns", she had to cancel her upcoming appearances.

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