National Crime Agency says demand and circulation of guns has gone up

Machine guns and assault rifles which could be used by terrorists or gangsters are increasingly being smuggled into Britain using the Royal Mail, police have warned.

Deadly weapons and ammunition ordered online are being smuggled into the country under the cover of the boom in the legitimate shopping trade.

The National Crime Agency (NCA) - dubbed 'Britain's FBI' - said postal and parcel services are now among the most popular methods to smuggle arms due to it being cheap and the low risk of getting caught.

Zoraki pistol recovered by police. A report detailed holes in the agency's intelligence as to why there has only been one seizure of a Baikal pistol at the UK border since 2009

Criminals are most likely to purchase firearms on the regular internet, with the 'dark web' - a secretive form of the internet, famously used for black market sales - being less popular because of the risks involved.

And while the dark web is a 'serious' risk, according to the NCA, many buyers are turned off using online services for the same fears as ordinary consumers, such as being scammed.

But crime fighters revealed they were struggling to work out how guns and ammunition make it past borders in a report released yesterday.

The report detailed holes in the agency's intelligence as to why there has only been one seizure of a Baikal pistol at the UK border since 2009, despite their use by British criminals being 'prevalent'.

Other recent seizures have seen Skorpion sub-machine guns brought into the UK using ParcelForce.

In one case, Alexander Mullings, 23, orchestrated the import of firearms from Germany to Britain from his cell in Wandsworth Prison.

Ammunition recovered by the police in mail system. Machine guns and assault rifles which could be used by terrorists or gangsters are increasingly being smuggled into Britain using the Royal Mail, a report has said

The report said: 'The NCA assess that the circulation of, and demand for, firearms and "mass casualty weapons" has increased within the criminal market place.

'Firearms continue to enter the criminal market through a variety of means, including direct importation through post/fast parcels and thefts from legitimate firearms holders or dealers.

'In the UK, post and fast parcels are likely to constitute one of the most popular methods of illegally importing firearms and firearms components.

Alexander Mullings, 23, orchestrated the import of firearms from Germany to Britain from his cell in Wandsworth Prison

'This may be due to the fact that the smuggling of firearms using mail parcels is perceived as being particularly cost efficient (although the numbers of actual firearms seized in post/fast parcel importations remain low).'

The report added: 'The purchasing of firearms via the dark web is a relatively small threat, albeit a serious one.

'It is risky for a customer as there's no way of knowing whether it is a scam or not.'

It noted five Baikal together with silencers and 35 rounds of ammunition were found hidden in 'meat products' aboard a postal bus from Lithuania at Dover in October 2015.

The report went on: 'This is the first time Baikal pistols have been detected at the UK border since 2009, although their continued use in criminality in the UK is prevalent.

'The NCA is currently investigating this importation.'

Ammunition is also rarely seized in the post but the NCA has recently uncovered components for production in a house.

The report read: 'It is unclear how criminals in the UK source ammunition.

'Ammunition can be made using presses and firearms powder.

'It is likely that importation through ferry ports or diversion from legitimate supplies feeds criminal supply.