NSW Police has issued a warning to people looking to fill Christmas stockings with illegal weapons this year - it won't be Santa arriving at your doorstep.

"With Christmas only one week away, we want the community to be aware of the dangers associated with prohibited weapons like the RS-X7 'Doomsday' Slingshot Crossbow," Drug and Firearms Squad Commander Det Supt John Watson said.

"We are calling on those in the community who have a slingshot crossbow or other prohibited weapons in their possession to surrender the items to police immediately - otherwise detectives will soon be on your doorstep to seize them."

Since August this year, the NSW Police Force has received information relating to the illegal importation and possession of the 'Doomsday' slingshots from the USA and Supt Watson said they represent a major threat to the safety of the community and emergency services personnel.

NSW Police also put together a demonstration video showing the awesome power of the slingshots which are capable of firing metal, glass and clay ball projectiles and are often marketed online as "shooting toys".

Australian Border Force International Mail, Cargo Clearance and Systems Support NSW, Superintendent John Fleming, said people should think twice about trying to bring the slingshots into Australia.

"Every day, ABF officers use advanced x-ray technology, intelligence, detector dogs and their own intuition to detect and stop illegal weapons at the border," Supt Fleming said.

"Our highly trained officers have already made almost 18,000 detections of prohibited weapons this year, including crossbows, imitation firearms, knives, knuckledusters and electric shock devices.

"Buying one of these weapons could end up costing you more than you think. Attempting to import prohibited items means you'll lose your money; lose your gift and you could face a fine or charges," Supt Fleming said.

To surrender a prohibited weapon, contact your local police station for advice and before attending. Under no circumstances should loaded firearms be taken into public places - including police stations.