A choking cloud of red dust has severely disrupted flights at Sydney Airport.

According to Australian media reports, the dust cloud originated in Australia's outback and will only begin to dissipate in the late afternoon.

Both domestic and international flights have been delayed. Some inbound international flights have been diverted to the northern city of Brisbane.

"Sydney is experiencing a sever dust storm today which is impacting the majority of both international and domestic flight arrivals and departures," says Qantas. "All international flights have been diverted to Brisbane or Melbourne this morning."

"It's a very unusual event to see a blanket of thick dust like this cover such a large area of New South Wales," Bureau of Meteorology regional director Barry Hanstrum is reported as saying. "We see [dust storms] fairly regularly but what we don't see is dust this thick make it across to the coast."

"More than half the state at midday today is under this cloud and the dust is starting to spread north and east and is likely to affect parts of Queensland as well in the next 24 hours."

Source: Air Transport Intelligence news