Heavy fog causes flight delays and ferry cancellations in Sydney

Heavy fog in Sydney has caused flight delays and saw all ferries services suspended.

The cloud has blanketed parts of the city's west and Sydney Harbour, with the Opera House and Harbour Bridge hidden from view this morning.

Domestic delays at Sydney Airport are averaging around an hour, with international flights about 30 minutes behind schedule.

Passengers are urged to contact their airlines for updates.

Sydney Ferries services are running again on Sydney Harbour after the fog saw all trips cancelled.

Passengers are advised to allow extra travel time and check indicator boards as services return to normal.

Drivers are also advised to take extreme care on the roads.