Council officers discovered men living mattress to mattress inside a run-down flat above a commercial premises during a dawn raid.
Police and licensing enforcement officers entered the converted one-bedroom flat in Brent, north London, shortly before 6am one morning last week following complaints from neighbours about the number of people hanging around outside the property.
Officers found 16 men crammed inside three rooms chock-full with bunkbeds made out of bits of wooden pallets. The tenants were sleeping seven, five and four to each room.
Some of the men claimed not to have any contact with the landlord of the unlicensed House in Multiple Occupation.
"These tenants are being exploited and forced to live in appalling conditions by a landlord who has no regard for their safety. They are living in a fire trap that is uninhabitable, grossly overcrowd and insanitary. People renting in the private sector in Brent are entitled to live in homes that are safe and well-managed" says a council spokesman.
An investigation is now under way to track down the identity of the landlord. Some of the tenants said that they had only been living in the property for a few days.