4 September 2012 Last updated at 04:31 ET

Rise in cannabis farms in Gloucestershire

Police say they will continue to target large-scale cannabis production in Gloucestershire after figures showed a rise in the number of farms.

Figures obtained by the BBC show the number of farms in the county has gone up by a third in the past three years.

In 2009 police found 38 farms, but in 2012 that number has risen to 60.

Det Supt Alex Drummond said the force would deal with large-scale growers but would only tackle those growing for personal use "if we come across it".

A farm is classified as 10 or more plants being grown or anywhere where conditions have been created for cultivation.

Det Supt Drummond said the large-scale growers had become more clever about hiding the farms.

'It has tunnels'

"We've had some really bizarre examples from converted houses to converted warehouses," he said.

"One more recent one was an actual underground storage container... with purpose-built containers sunk into the ground to try and disguise its location.

"It has tunnels down into it," he added.

Allen Morgan, a former policeman and drug expert, said: "It's not something that the police can ignore.

"There is obviously an air of criminality around and associated with it but they have to balance with other priorities like the heroin and crack cocaine markets.

"It's a very difficult thing for the police to manage at the moment."