New South Wales police say operations at the Sydney Opera House and in Manly were a precautionary and based on information from social media.
The operation is now over.
It began just after 3pm (local time) and everyone at the Opera House was evacuated.
The bar was closed and all tours of the iconic landmark were cancelled. Ferries from Manley to Circular quay were also either cancelled or delayed.
Police are also searching the Manly Ferry Terminal in a second operation they have confirmed is linked.
Police won’t say what is going on or what the operation is about but 3 News understands they received some information, which led to the evacuations.
It has been reported it was threat of some kind, but it’s understood so far nothing sinister has been found.