Scores of guns have been seized and 10 people arrested as part of a nationwide operation targeting customers buying illegal weapons.
Police from 25 forces and regional organised crime units raided a series of addresses on Wednesday in an operation co-ordinated by the National Crime Agency.
At least 61 firearms were seized including 46 handguns, five revolvers, two stun guns, a sub-machine gun and 1,000 rounds of ammunition.
Police also confiscated a quantity of Class A drugs, £2,000 cash, a kilogram of cannabis, eight Rolex watches and two crossbows.
The NCA said the 10 people arrested had been previously identified by investigators as having bought Flobert or blank-firing weapons online from sellers in eastern Europe.
Flobert guns are lethal in their original state and many of the blank-firers purchased were readily convertible to chamber live ammunition.
The NCA said that while both types of weapons are illegal in the UK they are freely available in countries across eastern Europe and can be purchased online for less than £100.
NCA firearms threat lead Simon Brough said some of the firearms were found buried in people’s gardens.
He added: “This operation highlights just how important it is for us to tackle the importation of illegal firearms into the UK. The mere availability of these firearms creates a range of significant risks to the public.
“The level of gun crime in the UK is one of the lowest in the world and strict UK legislation means it’s harder for criminals to access illegal weapons here.
“But we must continue to identify the supply routes by which illegal firearms enter the UK and collaborate with police forces and international law enforcement agencies to disrupt the criminal gangs using them.”
Of those arrested, four people have been charged with various firearms offences and remanded in custody.
Nathan Hughes was charged with three offences after Devon & Cornwall Police officers seized three firearms and a sub machine gun that he had dismantled and buried in various locations in his garden.
The 41-year-old from Redruth, Cornwall’s charges included the armed robbery of an off licence in Redruth.
Robert Lockhart and his partner Carol Stirling were arrested by the NCA and Police Scotland’s Organised Crime Partnership after a number of firearms and weapons were seized from their home.
The two 49-year-olds from Appin in north west Scotland were each charged with seven firearms offences.
Cambridgeshire Police arrested 26-year-old Calvin Jackson at his home in Peterborough, Cambridgeshire.
He was charged with six offences following the seizure of seven handguns, ammunition and class A and B drugs.
NCA officers also detained a 40-year-old man at Birmingham Airport after he landed on a flight from Jamaica and found a machete and CS gas canister in his car which he had parked at the airport.
A search of his home led to the seizure of five firearms, eight further CS gas canisters, three stun guns, ammunition, another machete and a baton. He was released under investigation.
Other arrests include a 15-year-old from Ryde, Isle of Wight, a man aged 53 from Shipley, Yorkshire and a 40-year-old man from Slough in Berkshire.
A 36-year-old man from Bristol, a 38-year-old man from Salisbury in Wiltshire and a man aged 60 from Peterborough were also arrested.
All six were released under investigation.