Sydney:
Police have cautioned Australians to be vigilant after an Al Qaeda-linked online magazine published a picture of Sydney's iconic Opera House.
They have expressed concern about the influence on the local Islamic community of the magazine's extremist literature.
Andrew Scipione, the head of New South Wales state police, said Thursday the publication of the picture is "a really important wake-up call for us all."
He says "we should never become complacent" about preventing terrorism.
Police are unclear about the significance of the picture in the latest issue of Inspire. The English-language online magazine published by associates of Al Qaeda in the Arabian Peninsula. The picture was carried without any comment.