Thousands of illegal and restricted weapons, including machine guns, swords and "stun gun knuckle dusters", are being seized at the New Zealand border every year.

Figures given to The Dominion Post show 13,801 items classified as weapons were intercepted by the New Zealand Customs Service between January 2010 and July 2012 - an average of more than 14 a day.

The detailed breakdown of items, discovered at airports, seaports, mail centres and during raids, revealed weapons ranging from simple knives to stun guns disguised as lipstick cases.

Rifles and shotguns were the most common firearms intercepted, but several machineguns were also found.

Bladed weapons included double-edged daggers, throwing knives, flick knives and even a spear. More unusual items intercepted were blade-like "claws", a mace and "stun gun knuckle dusters" that deliver a 950,000 volt shock along with a punch.

Customs investigations manager Shane Panettiere said most weapons were found at mail centres or airports, although some were arriving through international courier companies.

Measures used to detect suspect items included X-rays, physical inspections and sniffer dogs, and certain addresses known to Customs were also monitored.

Some people who attempted to import weapons were genuinely unaware that the items were illegal, but most knew what they were risking, he said.

"There are people who are just being naive but they're really the minority . . . Our laws are pretty much the same as the rest of the world."

It was impossible to know what percentage of items made it past checks but police had indicated most firearms used in crime were sourced locally or stolen rather than imported from overseas, Mr Panettiere said.

Most firearms arrived from the United States; Asian countries were common sources for items like stun guns.

Earlier this week two Hastings men, aged 19 and 21, were arrested for carrying stun guns disguised as cellphones. They had been using the weapons on themselves.

Sergeant Bob Gordon believed people were bringing the weapons in from Bali and Thailand.

Personal use of Tasers and stun guns in New Zealand is illegal.

Mr Panettiere said stun gun importation was rising, but he believed the guns were being brought in for criminal rather than personal use.

"The ones that we have intercepted, they've been known to be going to people with criminal backgrounds or relationships."

Almost all weapons seized are destroyed, though some antique items are given to museums.

THE CACHE OF SEIZED WEAPONS

January 2010 – July 2012

Throwing Knives - 1193

Flick Knives - 1140

Double-edged Daggers - 44

Gravity Knife - 1

Shotguns - 111

Stun Guns - 124

Swords - 56

Machine Guns - 4

Rifles - 386

Spike Sets - 167

Throwing Stars - 243

Claws - 12

Double-edged Spear - 1

Stun Gun Knuckle Duster - 1

Source: NZ Customs

* Figures do not include weapons intercepted at mail centres.

- © Fairfax NZ News