Councils are cracking down on tenants ripping off other tenants by posing as bogus landlords often in death-trap properties.

One tenant running a sub-letting scam in London was fined £20,000 for breaking shared house management rules and health and safety breaches.

A gang running a similar scheme in Peterborough, Cambridgeshire, was raided and booted out of the property before they could con any tenants out of cash.

In London, Petru Dregan pleaded guilty to running his scheme at Willesden Magistrates Court. Besides the massive fine, he was ordered to pay £6,520 costs.

The court heard the house had walls caked in damp and mould, while doors, windows and smoke alarms were blocked up.

The floor in every room was covered with mattresses, while some had crude bunks made from wooden pallets and tarpaulins. One bedroom designed to sleep two was shared by 10 men.

The tenants were paying £50 a week for the accommodation.

“In a poorly managed property like this one, people’s lives are at stake. Landlords, agents and sub-letters who ignore licensing laws and the regulations around housing management will be hit hard with heavy fines,” said a Brent Council spokesman.

In Peterborough, the unnamed gang were sub-letting three shared houses, with tenants paying between £90 and £120 a week each for rooms.

Often, when properties are sublet, they are done so purely for financial gain,” said Rob Hill, assistant director for community safety at Peterborough City Council.

“The person subletting the property often has little or no regard for the wellbeing of the occupiers and little knowledge of the laws that govern the letting of properties; resulting in overcrowding, disrepair and breaches of health and safety and fire regulations.”

From October 1, sub-letting a home to five or more tenants requires a licence from the local council and renting such a home without a licence becomes a criminal offence.