The National Crime Agency said terrorists could get hold of hundreds of guns smuggled into the UK
A month-long crackdown on weapons following the Bataclan massacre in Paris resulted in 833 guns being seized and 228 arrests.
Although none of the arrested were terrorists, senior officers said there were 'potential links' between those with guns and terror suspects.
Weapons from eastern Europe were often linked to drug gangs with 80kg of drugs 4,385 rounds of ammunition and £575,000 in cash also being recovered.
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Guns seized included assault weapons, AK74s, Skorpion sub-machine guns and Zoraki and Makarov pistols, one in the handbag of a woman.
Only 379 of the guns seized in raids carried out by the National Crime Agency could be fired.
One assault rifle along with 29 rounds of ammunition was discovered in London just hours before Remembrance Sunday.
Paris Terror Attack 2015: One year on Sun, November 13, 2016
Terrorists slaughtered 130 people during a series of coordinated terror attacks in Paris on Friday 13th November 2015. The attacks took place at the Bataclan concert hall, Boulevard Voltaire, Belle Equipe bar, rue Fontaine au Roi, Petit Cambodge restaurant, and Le Carillon bar.
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French President Francois Hollande and Paris Mayor Anne Hidalgo lay a wreath of flowers as they unveil a commemorative plaque next to the
Nick Wilcox, Detective Superintendent of National Counter Terrorism Operations said: "Since Paris there has been a requirement in order to make it harder for anyone to get firearms.
The fear is that we don't want people to get any firearms
Nick Wilcox, Detective Superintendent of National Counter Terrorism Operations
"Of those 800, 379 are actual firearms and 282 were arrested, there is definitely a correlation between firearms and drugs.
"Of those who have been arrested zero were terrorists.
"There are associations and potential links within communities between people holding firearms and counter terrorism persons of interest.
A raid after the Paris Bataclan massacre resulted in 833 guns seized and 228 arrests
"Those links are not strong links but they are enough.
"Communications and associations, it's people they are in touch with they have been in contact with but the extent of their relationship that's what we are seeking to build on.
"We have identified a number of associates and we are now trying to build up a picture of the extent of those associations.
"As a result of Paris we have strong legislation in place and robust mechanisms and police actively pursue firearms.
"The fear is that we don't want people to get any firearms so whether it's an automatic weapon like a Bren gun each of those could be far more impactive than say what happened in Leytonstone.
"We have strong borders, much better legislation and restriction in place however it is a constant battle.
"From what we have seen there are links to Lithuania and Bulgaria, a small percentage of the 379 guns that were seized can be linked to those countries."
Between 31 October and 26 November last year anti-terrorism squads arrested 282 people and seized over 80kg of drugs 4,385 rounds of ammunition and £575,000 in cash.
In total 111 arrests over the four week period were firearm related.
Handguns and shotguns remain the most prominent weapons of choice for criminal groups.
Senior officers claimed there were ‘potential links’ between the guns and terror suspects
In the early hours of Remembrance Sunday police stopped a group of four men in north-east London and found an AK74 rifle with 29 rounds of ammunition in the boot.
The four men were later charged with firearms offences and are currently being dealt with by the courts.
Chris Mckeogh, Deputy Director of the National Crime Agency, said: "The mess that gun makes when you are shot with it is quite significant.
"That in the hands of criminal drug dealers in north-east London is not the norm, it is quite worrying."
Mr McKeogh said: "The UK is isolated and does experience low firearm related cases in comparison to elsewhere.
"The firearms that are used are used to enforce, to make sure they can pursue criminal endeavours.
"In Britain there are 1.8m lawfully held firearms. These are good folks and understand how to take responsibility but it is the case that these fire arms get lost or stolen, like the weapon used in the Jo Cox murder."
Det Supt Wilcox added: "The next stage is to identify what access there is within these communities.
"If you were going to buy a firearm, where would you buy it from?"
In an investigation in the north east seven handguns, including two Makarov pistols, a sub-machine gun, six silencers and over 1,000 rounds of ammunition were seized.
Hours before Remembrance Sunday one assault rifle with 29 rounds of ammunition was found in London
Police also seized a kilogram of cocaine, 3kg of cutting agents and £30,000 in cash and arrested four men and one woman, who had a Makarov in her handbag.
NCA Director McKeogh said some guns are hired by "armourers" while others can sell for as little as £300.
He said: "Two of these guns were Makarovs, they don't care who they sell to."
"A firearm can change hands for abound £300 and some can change hands for even more.
"There is also a service where people will hold weapons, like an armourer, people will offer that service.
"All the ammunition that was seized was live and compatible with the weapons discovered."
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