Talk cancelled: Uthman Badar.

Talk cancelled: Uthman Badar. Photo: Facebook

The Sydney Opera House has cancelled a controversial talk by Muslim writer and activist Uthman Badar titled "Honour killings are morally justified" after widespread condemnation of its inclusion in the Festival of Dangerous Ideas.

In a statement the Opera House appeared to blame the talk's title for giving the "wrong impression", while announcing that it had decided not to proceed with the session.

"The Festival of Dangerous Ideas is intended to be a provocation to thought and discussion, rather than simply a provocation," the Opera House wrote on Facebook.

"It is always a matter of balance and judgement, and in this case a line has been crossed."

"It is clear from the public reaction that the title has given the wrong impression of what Mr Badar intended to discuss. Neither Mr Badar, the St James Ethics Centre, nor Sydney Opera House in any way advocates honour killings or condones any form of violence against women."

Mr Badar told Fairfax Media on Tuesday that the session's cancellation is revealing of the extent and influence of Islamophobia in Australia.

He blamed "baseless hysteria" for gagging the expression of ideas.

"It also highlights, once more, that freedom of speech is a tool of power and nothing more," he said.

By Tuesday night the link to Mr Badar's talk on the Festival's website had been taken down.

Honour killings are the murder of women deemed to have brought shame or dishonour on their family.

Uthman Badar was scheduled to argue that such acts are seized on by Westerners as a symbol of everything they dislike about another culture.

The announcement sparked condemnation and calls for a boycott on social media from those arguing the Opera House stage should not be used as a platform for such radical and confronting propositions.

Eleanor Gordon-Smith, a writer and ethics student, previously organised a series of talks at the University of Sydney designed to challenge orthodox ideas. She said the inclusion of Mr Badar's presentation looked like a marketing stunt to shock people and prove the festival can live up to its "dangerous" title.

"I think it's free speech and outrage for its own sake, not for the sake of seeking truth," Ms Gordon-Smith said. "If it's not hate speech, it's seriously ignorant speech."

Joint founder and co-curator of the festival Simon Longstaff said the idea is one he had consistently nominated for six years, because the point of the event is to push boundaries "to the point where you become extremely uncomfortable". He said Mr Badar has consented to the title and description of the presentation.

Before it was cancelled, co-curator Ann Mossop told Fairfax Media the speech would "obviously" not advocate honour killings but would discuss the framework in which the killings take place. She said many of the other sessions will present ideas that are considered "feminist" such as "Women for sale", a discussion of sex trafficking.

Mr Badar is an Australian spokesman for Hizb ut-Tahrir, a group described by the festival as "global advocacy group working for positive change in the Muslim world via the re-establishment of the Islamic Caliphate" - a state under sharia, or Islamic law.

In May, a 25-year-old Pakistani woman, Farzana Parveen, was stoned to death on the streets of Lahore by her family. She was three months pregnant at the time. A few weeks later, 18-year-old Saba Maqsood was shot twice and thrown in a canal (but survived). Both women's crime was to marry a man of their own choosing.

The United Nations reports that about 5000 women are killed in such circumstances every year.

Feminist author Eva Cox said the inclusion of Mr Badar's presentation was "tacky" and possibly unethical if the title turns out to misrepresent the extent of his argument. She said it carried the risk of further demonising Muslims in eyes of many Australians.

"You're setting somebody up to knock them off in a sense," Ms Cox said. She noted "honour killings" take place in several religions and are more of a cultural phenomenon practised in the Mediterranean and North Africa, rather than being particular to Islam.

The festival is on August 30 and 31.