The gang convicted of smuggling one of Britain's biggest ever gun hauls bought the "evil cargo" of automatic rifles and sub-machine guns from the same Slovakian supplier as those used in the Charlie Hebdo massacre.

Mastermind Harry Shilling, 26, from Swanley, and his accomplices - who smuggled the weapons on a boat into Cuxton Marina - also trafficked the poorly-deactivated military weapons through the same route used by the Al-Qaeda in Yemen jihadis who attacked the satirical magazine's headquarters in Paris, killing 12.

Shilling and Michael Defraine, 30, were convicted at the Old Bailey of smuggling 31 automatic rifles and machine pistols "capable of unleashing carnage on a terrifying scale".

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Defendants John Smale, 58, of Rochester, and Jennifer Arthy, 42, of Cuxton, were cleared of the charges.

Three others - Shilling's "loyal lieutenant" Richard Rye, 24, Arthy's partner-of-eight-years David Payne, 43, and Christopher Owen, 30 - previously pleaded guilty.

The gang's haul of 22 VZ58s, dubbed the "Czech AK47", nine Skorpions and more than 1,000 rounds of ammunition were said to have had four-times the fire-power of the arsenal that killed 130 in the latest Paris attacks.

VIDEO REPORT: Smugglers bought gun haul from Charlie Hebdo supplier. Ben Kennedy reports

But despite the assault rifles' capabilities of mass devastation they were legally sold until July 2015 as "acoustic expansion weapons", meaning they were disabled by a simple pin through the barrel.

The assault rifles were simply reactivated with a hammer and a metal rod making them able to fire 800 rounds per minute once again.

The details can be revealed today after the gang - headed by Shilling - was found guilty by the jury.

Paul Morris, operations manager of National Crime Agency (NCA) armed operations unit, said: "The VZs are all viable weapons, but all of the assault rifles were deactivated in the source region, which we are saying is Slovakia, where they were bought and, in the black market, they were re-actived before coming to the UK."

Rob Lewin, NCA head of special operations, Gold Commander of the operation, added: "We've got very similar weapons to those that were used in the Charlie Hebdo attacks.

"[And it's the] same supply route and same methodology of deactivated and reactivated.

VIDEO: 'Just imagine how much carnage that could cause in the wrong hands', head of NCA special ops Rob Lewis gives details of the haul

"We think they have come from the same source in the same country."

The officers were unable to discuss who the source was and were unable to say whether they were legally purchased before the law change.

An investigation is currently under way to determine the country of reactivation, they added.

Mr Lewin said: "For us what was quite shocking is that we seized four times as much fire-power on this job as used in the most recent Paris events.

"It's probably the biggest seizure we've ever seen on the mainland of these types of weapons."

The assault rifles could fetch between £2,000 and £4,000 in the UK after being purchased for as little as £118 in Slovakia.

NCA gun specialist Vince Philpott said the deactivation pin can easily be removed using a "metal rod and a hammer and you can knock it out and it's good to go".

Anyone aged 18 and over could purchase the weapons in that form until the Slovakian government changed the law in the wake of the Charlie Hebdo massacre.

Shilling's haul was shipped in on a boat named the Albernina to the River Medway marina on August 11 from Boulogne-sur-Mer, France

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When opening his case, Duncan Atkinson, for the prosecution, said: "The prosecution's case is that the importation was conceived of, planned and paid for by Shilling.

"He used his associate Defraine as his man on the continent, arranging the mechanics of the transportation of the weapons, and an associate called Richard Rye as a go-between with those who would do important leg work necessary for actually bringing the firearms into this country.

"The weapons were brought into the country from the continent aboard a boat called the Albernina, which was skippered by a man called David Payne, who is Jennifer Arthy's partne, and another man called Christopher Owen to acquire and prepare the vessel and to unload its evil cargo."

Mr Atkinson added that the mob intended the haul to be used as "lethal weapons capable of unleashing carnage on a terrifying scale - and they clearly intended to profit from doing so".

Shilling bragged "we now officially gangsters" in a text to Defraine after the guns were ferried across the Channel from Boulogne-sur-Mer, France.

A short while later the gang was arrested in co-ordinated armed raid at the marina and Homebase in Orpington, south east London, where Shilling, Defraine and Rye, were buying the equipment to bury the haul.

VIDEO: Police close in on the boat

Shilling and Michael Defraine, 30, of Bexleyheath, south east London, were convicted of conspiring to import firearms and another count of possessing firearms with intent to endanger life.

The gang now face lengthy jail terms after being convicted at the Old Bailey where security had been on high alert throughout the trial to block any breakout attempts.

They will be sentenced on May 13.