Cannabis factories on the rise in Kent Published duration 24 April 2015

image copyright PA image caption Campaigners say many of the "factory" workers have been trafficked and are in forced labour

The number of cannabis farms found in people's homes has risen dramatically in recent years, the BBC has learned.

More than 300 were found by Kent Police in 2014 compared to just over 100 in 2009, home office figures reveal.

Police say cannabis production is highly profitable for organised criminals who are seeking to finance other crimes.

Anti-slavery campaigners say many of those arrested have been trafficked into the country and forced to work.

Between August 2013 and August 2014 there were 316 cultivation of cannabis offences logged by Kent Police - in 2009 there was just 109.

Medway was the highest affected area with 59 cases, followed by Swale with 48 and Thanet with 37.

'Huge great holes'

Andrew Wallis of charity Unseen told the BBC many of those arrested have been trafficked into the country and forced to work in "bonded slavery".

He said: "Children have been found in these cannabis factories used as gardeners, but are often locked into the premises and forced to work in very unsafe environments."

The factories are also proving a worry for landlords who often find they are not insured against damage caused by the criminal activity.

Marion Murray of the National Landlords Association said: "They have got to have extensive water and cultivation and fresh air coming onto the plants, so they drill huge great holes across the house.

"They are not worried about the structure of the property. You can go in and it has actually been decimated as they have changed your living accommodation into large greenhouses.

"Water damage is extensive; they bypass your electricity making it very dangerous. It is power intensive so they will be finding ways of going into the national grid in a very dangerous fashion."

She warned landlords: "The police message is: don't mess with the criminals as a lot of these properties are booby-trapped."