The Sydney Opera House precinct was evacuated and the Manly ferry wharf searched on Thursday afternoon after information NSW Police received via social media, the Sydney Morning Herald reports.

The forecourt of the Opera House was cleared about 2pm on Thursday, January 14 with police erecting metal barriers.

Police said the operation was a precautionary measure. Searches by officers at Manly and Opera House concluded just over an hour later with nothing uncovered.

Fairfax Media understands the operation was sparked by a bomb threat on board a Manly ferry.

NSW Transport said the 1.20pm ferry from Manly to Circular Quay was cancelled due to the operation, while other journeys on that route were delayed.