One of Britain's biggest ever cannabis factories has been discovered in a maze of underground mining tunnels.

The drug den is so big in fact - that police admit they are still to find all of the drugs stashed in the caves.

Glasgow Times:

Detectives found the huge cannabis factory hidden deep inside the vast maze of underground tunnels on Thursday.

The discovery was made at Bethel Quarry in Bradford on Avon, Wilts, after a search warrant was executed.

Glasgow Times:

Remarkably hidden inside the disused quarry, the drugs haul were being stored in tunnels once used by Heinz to grow mushrooms for its soup.

The tunnels form part of a former limestone quarry covering about 10 acres or 40,000 square metres.

Glasgow Times:

Officers began exploring the mines after uncovering the drug den and say they are discovering more and more places where cannabis was being grown underground.

There are extensive mines and quarries in the Wiltshire Cotswolds that date back centuries and have been repurposed for everything from storing million pound bottles of vintage wine to a centre for British intelligence communications.

Glasgow Times:

The mine complexes stretch from near Corsham and the famous Box Tunnel, down to near the town of Bradford on Avon.

Mining stopped at the end of the 19th Century and the tunnels were used by the War Office in 1939 to store naval equipment.

After WW2 the quarry was used by the Heinz company to grow mushrooms for soup.

Glasgow Times:

The quarry tunnels were sold in 2011 and advertised as being supplied with electricity and water.

In 2015 a group of explorers reported that the site had been closed for years, “but recently we found it wide open. Not only open, but the electricity and lights were on.”

One explorer claimed he had been “physically assaulted by some thug wielding a baseball bat, who accused them of breaking in”.

Glasgow Times:

Inspector Nick Mawson of Wiltshire Police said: "Local residents are likely to see police presence at Bethel Quarry and surrounding area as officers carry out searches and gather evidence.

“This work is anticipated to carry on into next week due to the size of the location and safety issues at the site and we appreciate the patience of the community."

Two men were arrested and subsequently charged with the production of cannabis (Class B drug).

Alksander Shyti, 45 and Altin Deda, 39 were due to appear at Swindon Magistrates Court on Friday.