Concerns about firearms falling into terrorist hands are running high after a record level of gun seizures in London and similar spikes in Manchester, Birmingham, Leeds and Liverpool.
Authorities fear that links between street gangs and terrorists could give extremists access to weapons and risk the type of mass shootings most recently seen in the Paris attacks.
Mark Rowley, national policing lead for counter-terrorism, said: “Half of the plots that have been disrupted in recent years have involved terrorist plotters who tried to get hold of guns.
“The links we see tend to be from terrorists into criminals in the communities they hail from. It will often be people involved in low-level organised crime or gang activity.
“You do get gang members, criminals, people who are already angry, difficult people causing problems in communities, who perhaps get given a more clear purpose for their violence by a terrorist ideology, whether they pick that up on the streets or in prison.
“Those gang criminality links are an issue that concerns us and we have seen evidence of it potentially linking firearms into terrorism.”
At least 10 terrorist attacks have been foiled by British security services and police in the past two years.
Yesterday, the National Crime Agency (NCA) and counter-terrorism police launched a major campaign to try to clamp down on the supply of illegal guns into the UK.
NCA director Lynne Owens said disrupting the supply of firearms has “never been a more significant priority”.
“Currently we believe we hold an advantage,” she said. “There is low availability of illegal firearms in the UK compared with European and international partners, but it is not an advantage that we take for granted, and to maintain that advantage we must not stand still.”
There are estimated to be about 750 crime gangs in the UK who are involved with guns.
Last month, Britain’s most senior police officer Sir Bernard Hogan-Howe warned more weapons were ending up on the streets of major UK cities, with a record 714 seized in London in 2015.
Ms Owens said: “These criminal networks think nothing of who they supply their weapons to and they represent a significant risk or route by which an extremist or an extremist group will try to access the type of weapons that we did see used in attacks in Europe. One gun in the wrong hands in a public space is all it takes to cause devastation.”
Members of the public are being urged to pass information to police or Crimestoppers about guns being smuggled into the country, or legally-owned weapons being stolen.
Around 800 legal firearms go missing each year and there are thought to be thousands of illegal guns in circulation in Britain.
An attack by marauding gunmen is considered to be the most significant terrorist threat and last week a review of London’s counter-terrorism arrangements suggested that UK border security should be stepped up. The Home Office insisted the UK has “one of the most secure borders in the world”.