Cleaners at the Olympic Park are being housed ten to a room in 'slum' conditions at a huge temporary compound.
The campsite in East London, hidden from public view, has 25 people sharing each toilet and 75 to each shower.
They sleep in portable cabins, some of which have been leaking in the rain.
And the bad weather has left the site flooded with stagnant water, forcing them to use abandoned crates as makeshift 'stepping stones' to move around the site.
Hundreds have come from abroad to work at the Olympics despite promises that the jobs would go to Londoners.
On arrival, some were horrified to be told there was no work for two weeks. But despite this, they were made to pay the cleaning company £18 a day in 'rent' to sleep in the overcrowded metal cabins, which works out at more than £550 a month.
Others who had come to the UK desperate for the jobs turned back, describing the camp as 'horrible', with showers and toilets 'filthy' from over-use.
Andrea Murnoz, 21, a student from Madrid, said: 'I couldn't believe it when I saw the places people were sleeping.
'When I first saw the metal gates and the tall tower in the middle, it reminded me of a prison camp. It looks horrible. I was thinking I would apply for a job, but I have changed my mind. My two friends signed up, but I think they are regretting it.'
Cleaners at the camp have signed gagging orders preventing them from talking to the Press and have been banned from having family and friends visit 'for security reasons'.
But one worker, from Hungary, said conditions were 'very bad' inside the camp but he had nowhere else to live. 'It is like a slum inside,' the 24-year-old said. 'The toilets are dirty and the space is very little.'
Another, also from Hungary, said: 'When we saw the camp, we were shocked. When we came to England we thought accommodation would be much nicer.
'Some of the cabins have been leaking and we have been told to fix them ourselves. Two girls have left already because they did not want to sleep in a room with men they didn't know.'
Plans for the accommodation were backed by London 2012 organiser Locog and waved through by the local council, Newham, even though environmental health officers said the toilet and shower facilities were 'unlikely to be adequate', while landscape architects said the sleeping arrangements were 'cramped'.
But councillors decided that because the camp would be only temporary, concerns about the housing and welfare of the workers were not 'justifiable reasons for refusing planning permission'.
Any accommodation where more than two adults have to share a room is considered 'overcrowded' under housing laws. Health and safety guidelines state that employers should provide at least five toilets and five washbasins for every 100 people.
Craig Lovett, of Spotless International Services which runs the camp, said the number of toilets and showers per person exceeded requirements for temporary accommodation and that there were internet, medical and entertainment facilities on-site. He said shift patterns would reduce pressure on the facilities.
He said unexpected heavy rain had been a 'pain' but the company was working tirelessly to sort things out.
He added: 'This is not a prison. Nobody is forced to stay there. Many of our staff have come from areas where there is extremely high unemployment and are very happy to be working in the Games.
'There will always be a couple of disgruntled people on site, but it's a shame they didn't come to talk to us to air their grievances because there are certainly processes in place for them to do that.'
A Locog spokesman said: 'Cleanevent [part of Spotless] have assured us that the accommodation they are providing their workers is of a suitable standard.
- Daily Mail