Armed police officers are patrolling the fields around Bethel Quarry in Bradford-on-Avon following the discovery of a large cannabis factory underground on Thursday.
Wiltshire Police obtained a warrant under the Misuse of Drugs Act to raid the property off Jones Hill, but say the size of the bunker and safety issues are causing delays.
Two Romanian men, Alksander Shyti, 45 and Altin Deda, 39, were arrested and subsequently charged with the production of Cannabis (Class B drug).
Inspector Nick Mawson 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.”