A series of photographs taken in the slums of Lagos shows the faces of sex workers living in squalid conditions.

And the images have a tragic undercurrent, with tens of thousands of people in the sex trade diagnosed with HIV each year, and millions dying from AIDS across Nigeria.

A study in 2013 found that nearly a quarter of Nigerian sex workers have HIV

A survey conducted last year has also highlighted that attitudes towards condom use is helping the spread of the condition, and research suggests that nearly a quarter of Nigerian sex workers have HIV.

The pictures were taken in a Lagos slum, where girls as young as 14 entertain up to five clients per day

The pictures were taken by photographer Ton Koene in Lagos, Nigeria's largest city

A woman stands next to an advert encouraging condom use, in a country where researchers found more needs to be done to change attitudes toward safe sex

The pictures were taken by photographer Ton Koeneon in a Lagos slum named Badia.

There are currently an estimated 1.2million people in Lagos, Nigeria's largest city, living with HIV.

He said his driver had quipped: 'If you arrive by car, you can smell the HIV virus outside.'

A man speaks to a woman in the Badia slum in Lagos, where hundreds of women work in the sex trade in order to survive

In Badia, sex workers as young as 14, trying to earn money to survive, entertain around five clients a day.

Last year a study by the Iranian Journal of Public Health noted that the country has a 4.1 per cent HIV/AIDS prevalence rate in adults.

Thanks to investment and education, the study found, the rate had fallen from five per cent in the early 2000s, but it said there is still some way to go.

Three years ago, research by the Journal of the International AIDS Society found the prevalence among sex workers in Nigeria was 24.3 per cent.

Last year's study said women often found they could not ask their husbands or boyfriends to wear condoms, and were not expected to carry them.

One respondent, a 28-year-old marketing executive, said: 'The problem is that you cannot even suggest the use of that thing to your boyfriend.

A sex worker smokes a cigarette in the series of photographs taken by photographer Ton Koene

'It’s like if you say it you are accusing him of sleeping around or that you are not sure of yourself. No matter which one, it can end the relationship and give you a bad name.'

It stated: 'To confirm this cultural barrier to access to prevention tools, only one female respondent... has ever gone to buy a condom for her boyfriend, while all the other female respondents were of the view that they would not like their parents and spouses to see them with condoms.'

A 42-year-old father of three told researchers in the study: 'Any woman, including my wife who tells her husband about it or gets it for them to use needs to be questioned. In short, she should be seriously sanctioned.'