More than 100,000 illegal exotic cockroaches - some as big as the palm of a hand - have been seized by Australian authorities from a commercial breeder in New South Wales.

The seizure, worth $AU200,000 ($143,000; £106,000), included Madagascar hissing cockroaches and dubia cockroaches from a breeder in Bathurst, 200km west of Sydney. Both species cannot be legally imported into Australia or kept, bred or sold.

It is the largest seizure of illegal exotic invertebrates, authorities said. The illegal insects can spread disease and harm native wildlife and agriculture, they added.

The illegal cockroaches, often fed to pet reptiles, will be killed and disposed of by authorities.

"We're seeing illegal breeding and trading of exotic cockroaches and we're putting pet businesses and pet owners on notice," a spokesperson for the Department of Climate Change, Energy, Environment and Water (DCCEEW) said.

"If you are found to possess, breed or trade exotic cockroaches such as dubia cockroaches and Madagascar hissing cockroaches they will be seized and you could face penalties under federal law."

The spokesperson urged reptile owners who have been using dubia roaches as feeders to seek legal alternatives such as crickets and wood roaches.

Madagascar hissing cockroaches, one of the largest species in the world, are so called because they can produce a hissing sound loud enough to be heard.

Bathurst snake catcher Stefanie Lesser said she had seen the illegal invertebrates being sold online as reptile food, according to the Australian Broadcasting Corporation (ABC).

"People do have them because they are big, they're sort of like the size of your palm of your hand," she told the ABC.

"They probably are cost-effective, rather than feeding each lizard three or four woodies, which are quite small, you could only give them one."