SYDNEY - AS Australians prepare to heap their tables with fresh seafood for Christmas, police said they have been trained to crack down on oyster theft.

Farmers have warned of an increase in oyster rustling during the summer harvest period, prompting police in New South Wales state to attempt to reduce the theft of the succulent delicacy.

'We've done some training up there at Port Macquarie and Forster with the fisheries department,' a police spokesman said on Monday in reference to two oyster producing areas.

Police will increase surveillance on oyster beds as well as the likely outlets for the stolen goods such as roadside vendors, he said.

Growers said while many farmers did not report the crime, oyster theft was a growing problem and a threat to the state's A$34 million (S$43 million) industry.

There are also concerns that unfiltered stolen oysters pose a health risk.

'The size of the pilfering that goes on is a concern,' chairman of the New South Wales Farmers Association's oyster committee Mark Bulley said.

'I think just about every river does have activity, it's just that some are greater than others,' he told The Sydney Morning Herald newspaper.

Black market sales of seafood in New South Wales are estimated to amount to between 30 and 60 per cent of the legal catch, experts say. -- AFP