Soco interviewed 216 tenants for the survey that was published yesterday. It also highlighted conditions in the so-called "small suites" - usually with a very small area containing a toilet and kitchen - that emerged in recent years and cost more than cubicles.

One tenant of a 50 sq ft "small suite" in Cheung Sha Wan, Kowloon, said he and his wife were paying HK$1,530 for his "suite" - one of 10 in the divided flat.

"We cook and use the toilet in the same area, the living standard is terrible," the 58-year-old said.

"The toilet window in our room is the only window in the whole flat. We can't close it even when my wife is having a shower. I am very sad about it but there is nothing we can do."

Another cubicle tenant said his family of four lived in a 100 sq ft space separated by wooden boards. The monthly rent for space, which has bedbugs, recently went up 9 per cent to HK$3,800. He said his family had been waiting for public housing for six years.

Government data showed in 2012 there were 71,000 people living in substandard flats.

Soco's organiser Gordon Chick Kui-wai said the survey found many living in these flats were single, middle-aged men and working-class families who could not get public housing. Mean monthly family incomes were HK$5,000 to HK$10,000.

"More than 80 per cent of the interviewees said they were having serious hygiene problems in their homes, especially those with a shared toilet and kitchen."

The Shadow Long Term Housing Strategy Steering Committee slammed the government's public flat supply target as "significantly insufficient" in reducing the lengthening queue of applicants. Committee spokesman Chan Siu-ming, estimated some 40,000 units would be needed a year to have an effect.