Housing inspectors discovered a man living in “coffin-like” conditions in a gas-meter cupboard beneath the staircase of an overcrowded property in east London, during a series of raids on poor-quality housing in the area.

Council staff found a young man asleep on a mattress inside the cupboard, in a space they described as less than one metre by two metres. Inspectors believe he was paying about £250 a month to rent the cupboard. His living space had no ventilation and no room for anything except the mattress on the floor.

Elsewhere in the same two-storey house they found six people sleeping on three bunkbeds, squeezed into a single bedroom. They believe 13 people were living in the house, which was also found to have numerous fire and electrical safety hazards.

Council staff found six people sleeping on three bunkbeds squeezed into one bedroom in the same property. Photograph: Andrew Baker/LBN

The mayor of Newham, Robin Wales, who has introduced landlord licensing in the borough, and who attended the raid this week, said: “It cannot be right in the 21st century, in one of the world’s wealthiest cities, a young man is being forced to pay hundreds of pounds to rent a cupboard under the stairs, sleeping alongside the gas meter.

“The scenes we saw on this visit are a timely reminder that, while by tackling bad landlords we are driving up standards, there is still much to do. That is why it’s imperative that the government allow us to continue with this work, and stop the exploitation of tenants.”

Eleven people were found to be living in the house, which also had numerous fire and electrical safety hazards. Photograph: Andrew Baker/LBN

The council was unable to reveal more details about the tenants renting the house, except to say that they were understood to be south Asian, and believed to be working legally in the restaurant industry.

During another raid in the borough on Tuesday, inspectors found three people living in a shed, where they were each paying £200 a month in rent. The landlords will be issued with penalty notices, which can be set at up to £30,000, depending on the seriousness of the conditions.

Wales, who has been campaigning to improve housing conditions in the borough, said he had never previously come across a landlord renting out a cupboard. “I was astonished that someone would think it was OK to put someone in there, to squeeze money out of them. I don’t know how they managed to get a mattress in the space, it was so tight,” he said.

“The tenants are decent working people, trying to earn a living. They’ve been exploited; the landlord is contemptible. We have prosecuted 1,200 landlords and banned a number of them, but it is a constant uphill battle.”