Inside Sydney's secret weapons haul

First on 7: Customs has revealed it stores some of the country's deadliest weapons in a secret location in Sydney.

7News was given an exclusive look at the lethal haul, which was seized from smugglers, the post and holiday makers.

This vault is so secret, we are not allowed to reveal its security measures or even the location.

This is the first time cameras have been allowed inside.

It is a vast armoury where customs stores hundreds of deadly weapons it seizes at the border.

For example, the AR-10 - a fully automatic centre-fire rifle that has never been legal in Australia.

Another weapon is the Steyr rifle used by Australian soldiers and an illegal high-calibre revolver.

Some come by mail, others are seized from private boats returning to Australia.

Tim Fitzgerald, of Customs Border and Protection, said: “We're aware of organised syndicates that attempt to bring those items into Australia for the sole purposes of using them to commit crime."

Last year, Customs and Border Protection seized more than 3000 firearms and replicas.

But it isn't just guns. One haul, from the last two weeks, made up mainly from holidaymakers' luggage, includes numchukas, flick knives and brass knuckles.

But the penalties might surprise some travellers.You can be looking at 10 years imprisonment and or a $425,000 fine.

If you're unsure if it is a banned weapon, the advice is to declare it at the border.