Landlords should be increasingly focused on the growing danger to property owners of cannabis farming, according to the insurer Aviva.

A recent report by the Association of Chief Police Officers (ACPO) highlighted the scale of cannabis farming in the UK and Aviva said property owners should be increasingly vigilant when “vetting potential tenants, as well as inspecting their properties, as cannabis farming continues to rise”.

The report released by ACPO shows that UK police forces detected more than 6,800 cannabis farms and factories in the UK in 2009-10. It adds that the types of premises used are becoming more varied with farms now uncovered in industrial buildings, former pubs, cinemas, nightclubs, hotels, print works and banks.

A recent example was seen in a police raid on an industrial unit in Westcott, Aylesbury, which found around 1,000 cannabis plants in various stages of production were being grown in 18 shipping containers in a warehouse.

Aviva said cannabis farming is putting landlords at an increased risk when letting their properties. In order to better protect themselves, landlords need to carry out some key actions to minimise the risk of a property being used for cannabis farming and to ensure reasonable precautions have been taken to avoid it.

Matthew Gordon, underwriting manager at Aviva, said: “As with most insurance policies, the duty of care element means landlords must protect their investment and minimise their losses. It is important to be aware of the warning signs and make sure all ‘reasonable precautions’ are taken.

“Employing a managing or letting agent can be money well spent. They will manage the tenant vetting process and carry out the inspection service on behalf of the landlord.

"Cannabis farming brings many increased risks and insurers could refuse a damage or fire claim, for example, if the landlord has neglected his responsibilities and not thoroughly vetted the tenant.”

Aviva has outlined the following tips for landlords to protect their properties:

Do not allow your property to be sub-let with no control of sub-tenant activities
Use a managing agent or letting agent, employed to vet tenants’ details, manage the property and carry out regular internal inspections
If you don’t use a managing agent, ensure that regular internal inspections of the property are undertaken and tenants are sufficiently vetted
Do not accept payment of rent in cash – insist it is paid through a bank
Be wary of short-term lets without first undertaking rigorous checks