CUCUTA, Colombia June 11 (Thomson Reuters Foundation) - Hymns sung at evening mass float from an open church door across a busy square in Colombia's border city of Cucuta, as about 20 Venezuelan sex workers wait for clients.
Crouched on the steps of a statue and surrounded by grubby motels, fast-food restaurants and bars, Andrea and Carolina say they fled Venezuela to escape hunger.
They now sell their bodies to support themselves and their families.
"If I don't do this, I and my children don't eat. It's that simple," said 26-year-old Andrea, who arrived four months ago, leaving her three young children with their grandmother.
"The money I send back home is what they survive on."
Her homeland is in the throes of economic turmoil with severe shortages of food and medicine, which the Organization of American States has described as a "humanitarian crisis."
About 672,000 Venezuelans have crossed into neighbouring Colombia alone, both legally and illegally, since 2015, according to Colombian authorities.
The exodus from the oil-rich country is the largest migration of people in South America's recent history, and it shows little signs of abating. For some, sex work is their final, desperate option.
In Cucuta's Mercedes square, young Venezuelan women wearing tight jeans and skimpy tops - some barely looking 18-years-old - sit on park benches as police officers patrol.
For Carolina, 30, a good day's work means getting three clients, which brings in about $30. A third of that is spent on a motel room to take clients to, as well as condoms, food and daily rent for a room shared with four other women.
"What I earn in a day here lasts more than a month for my family in Venezuela," said the mother of four.
The devaluation and hyperinflation of Venezuela's currency, the bolivar, means it has become virtually worthless.
Carolina said the monthly minimum salary in Venezuela only covers the cost of one kg of rice or a carton of eggs. The situation was so bad that she finally paid a gang $9 to cross into Colombia using illegal footpaths.
Until recently, she never imagined that she could end up selling sex in Colombia.
"I wasn't a prostitute in Venezuela. I had a proper job," said Carolina, who once worked as a company receptionist.
No one knows how many Venezuelan sex workers are now in Cucuta, a city of 800,000 people. On any given night, up to 20 can be seen in each of the three main central squares.
They share the squares and streets with other Venezuelans who peddle sweets, coffee and cigarettes for small change.
Some migrants beg with babies in their arms, while others sift through rubbish bags and rely on the kindness of local residents and church-run soup kitchens for a hot meal.
Venezuelan women also sell their hair.
In Cucuta's main leafy square, where dozens of Venezuelan hawkers work, a few men wear signs reading: "We buy hair."
Women receive $10 to $40 depending on the length and quality of their mane.
Scores more prostitutes work on street corners around the city's bus terminal and in the red light district, alongside Venezuelans sleeping on cardboard in the streets.
"We get the feeling that in certain areas and cities, there is a lot of survival sex," said Jozef Merkx, head of the United Nations refugee agency (UNHCR) in Colombia.
"It's not only with women, but with men, boys and children," he told the Thomson Reuters Foundation.
In response to the rising number of Venezuelan sex workers, Colombia's constitutional court ruled last year that they should be given work visas and have their rights protected.
Cucuta's mayor, Cesar Rojas, said he has restricted bar opening hours in parts of the city to address the growing number of sex workers, but he added that adult prostitution in designated red light districts is legal.
Venezuelans tend to charge less than their Colombian counterparts who are more likely to be found working in bars than on sidewalks, while teenagers can earn more than adults, Carolina said.
Andrea and Carolina say they are voluntarily working on their own, without a pimp. But local gangs charge them each about $2 a week to stand in the square.
"Depending on the areas and cities, there might be mafias behind the sexual exploitation," said UNHCR's Merkx.
"We are seeing more people coming into Colombia without a passport and who have no migratory status, which makes them vulnerable to labor and sexual exploitation," he said. "They do whatever they can to get money."
Other migrants try to find work as cleaners and street vendors, rather than turning to the sex trade.
"I'd rather go without eating than stand on the street doing that," said Sofia Salas, standing in line at a soup kitchen with her sons and hundreds of other Venezuelans.
"It's very sad to see, especially the younger ones, the 13 and 14-year-olds."
About 40,000 Venezuelans were crossing the border each month by late 2017, according to Colombian authorities.
Many walk over a crowded bridge that connects Cucuta with Venezuela, lugging suitcases and plastic bags, and pushing elderly relatives in rented wheelchairs under a blazing sun.
Those who settle in Cucuta are often Venezuela's poorest.
With no passport or money to pay for bus tickets, they cannot move on to other cities in Colombia, or follow hundreds of thousands of others to Brazil, Peru, Chile and Ecuador.
Back at Mercedes square, it has been a slow night.
"We'll be sending less money home this week," Andrea said.
Reporting by Anastasia Moloney @anastasiabogota, Editing by Jared Ferrie.
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