Five Hounslow landlords have been duped into renting their properties to tenants who turn them into drug-making dens.
Hounslow Council says it is now offering advice and financial support after its landlord liaison officer received the complaints about rented properties being transformed into cannabis factories.
In all five cases landlords had rented their property to a single tenant or couple of eastern Asian or south east Asian origin.
The tenants provided references which checked out perfectly and the rent arrived in advance each month for several months and inspections revealed no problems.
But after several months of good behaviour the tenant started ripping holes in the walls and fitting industrial coolers and gardening equipment associated with cannabis cultivation.
Because of the amount of electricity used the cannabis factories can become a major fire risk and power surges are often the first clue for police that a factory has been set up.
In the last financial year Hounslow police closed 25 cannabis factories.
The council is currently issuing grants to help landlords to repair damaged properties.
Councillor Mark Bowen, deputy leader of Hounslow Council and lead for strategic housing, said: "This is an extremely worrying problem and we are advising landlords to be vigilant.
"Landlords are being lured into a false sense of security by tenants who seem reasonable, check out perfectly, pay their rent on time, but have turned their properties into cannabis factories once a level of trust has been achieved.
"Our advice to landlords is to ensure you do proper checks on tenants and make visits every six to eight weeks. Small signs, like curtains being pulled during the day, can indicate wrongdoing."
Landlords who have been a victim of tenants using their property as a cannabis factory should call 020 8583 3869.
If a landlord suspects their property is being used to manufacture drugs they can call Hounslow police on 020 8577 1212 or email tx-biu@met.pnn.police.uk.
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