Four buy to let investors have each been fined £10,000 for letting out unlicensed HMOs.
The unlicensed properties , all in the Greenwich area, include a two-bedroom HMO rented to four separate tenants, a five-bedroom HMO rented to seven separate tenants, and two separate three-bedroom HMOs.
A council spokeswoman says: “Every single person in our borough deserves good quality accommodation and our licensing enforcement is instrumental in ensuring that landlords maintain high standards for their tenants.
“Most of our landlords are following the rules, but for those that aren’t, we encourage you to come forward and license your property before you are caught and risk being fined up to £30,000.”
The council says it is “actively identifying properties that are unlicensed in the borough and taking enforcement action” against owners.