SYDNEY (REUTERS) - Heavy fog caused delays and cancellations at Australia's busiest international flight hub, Sydney Airport, on Saturday morning (June 29).

There were 10 cancellations of domestic flights and delays of international flights, a Sydney Airport spokesman told Reuters at 8am local time (6am Singapore time).

While the fog had lifted by noon, delays of up to an hour for international and domestic flights continued, the airport spokesman said.

Travellers have been urged to check departure times with their airlines.

A Qantas spokesman said the airline had four flight diversions and minor delays but no international cancellations.

Virgin Australia said it had four cancellations due to the fog and advised passengers to check their online flight status page for information on their flights.

"There are still delays expected throughout the day," a Virgin spokesman told Reuters.