A plastic sheet, a blanket, a sleeping bag: a makeshift bed laid out in the shadow of towering apartment blocks by a man who would rather be homeless than cooped up in Hong Kong's cramped and overpriced housing units.

Bright-eyed, neatly turned out but painfully thin, 54-year-old Ah-po works in a warehouse by day.

By night he sleeps in the stands of a neighbourhood football pitch in an urban public park, and has done for three years.

In a city where the wealth gap is becoming an unbridgeable gulf, Ah-po is among an increasing number of low earners opting to sleep outside rather than in minuscule units known as "cubicle" or "subdivided" flats, apartments carved into tiny living spaces by landlords capitalising on demand as public housing remains in short supply.

"I work so hard in the day time -- I just hope to live comfortably and well in the evening," Ah-po told AFP.

"But nowadays the rent is so high."

He says he can make up to HK$12,000 ($1,500) a month when his health permits -- he suffers from arthritis -- and has been in and out of lower-rent accommodation since his business failed eight years ago.

However, with property prices rocketing in the past decade, even a unit measuring less than 100 square feet (9 sqm) can cost several thousand Hong Kong dollars per month.

There is no legal stipulation for landlords over minimum apartment size or provision of basic amenities.

Cubicle flats seen by AFP measured as little as 28 square feet, just enough room to squeeze in a bed. A grimy toilet and kitchen are often shared by multiple tenants. Even these units can cost around HK$2,000.

For Ah-po, the park is a more pleasant environment and removes financial pressure -- he fears his arthritis may stop him working, leaving him unable to pay the bills.

"I've got familiar with people who come here for morning exercise and we will greet each other," he says.

"I have a sense of belonging."

- 'Easier to sleep under flyover' -

Research by Hong Kong universities and NGOs shows the number of homeless rose to more than 1,600 in 2015, up 14 percent since their last survey in 2013.

More than a third have jobs.

"If they pay rent, (the accommodation) is small, it's hot, it's humid, there are many insects...If they go into the park or under the flyover it's noisy, but they can sleep," says Professor Wong Hung at the Chinese University of Hong Kong's department of social work.

The problem has got worse in the last two to three years as salaries have not kept up with rent hikes, Wong adds.

There are long waiting lists for public housing and temporary accommodation is often on the outskirts of the city, meaning extra cost to travel to work, Wong says.

Now the average age of the homeless is rising as they now tend to stay on the streets long-term.

The government says it is trying to "reintegrate" the homeless, with a range of services from emergency shelters to social security payments.

But campaigners argue it is not enough.

Authorities should focus on building low-cost dorms in urban areas where homeless people could settle for two or three years, says Ng Wai-tung, of the Society For Community Organisation (SOCO), a Hong Kong NGO helping the poor.

"It's very sad that people can't afford to rent a place even though they have work," says Ng.

- Hong Kong's McRefugees -

In a sign of increasing desperation, some of the city's poor are now turning to 24-hour fast-food restaurants for shelter.

The plight of these "McRefugees" was highlighted when a homeless woman was discovered slumped dead over a table in a McDonald's restaurant last year.

One former McDonald's sleeper, Angelina Sun, 56, says she stayed there overnight for several weeks when she split from her husband, jobless and afraid of being a burden on friends and family.

She now earns around HK$8,000 each month in a factory and is in temporary accommodation in a Christian-run female dormitory.

"The rental outside the dormitory is very high, even for a small studio," says Angelina.

She is resigned to paying half her salary for a tiny unit when her dormitory place expires.

"There will be no money left for entertainment, clothes, but I can make ends meet. I can survive," she said.

For others, McDonald's has become home -- retired factory worker Ko Wing-kam, 62, regularly sleeps there to avoid the bedsit he shares with nine strangers.

"I'm not happy with the situation, but there's nothing I can do," he says.

At the football stands, Ah-po is laying out his bed.

He has not told his family he is homeless. It is only after dark that he contemplates his fate.

"When I work, I'm ok. But when I come back after dinner, I will think about my ex-wife, daughter and family members," he says, staring across the dimly lit park.

"I feel hopeless."