Loreto Sister Imelda Poole has been fighting human trafficking for years and is now increasingly worried about the situation in Ukraine.

"There has been an explosion of child trafficking in the world in recent years because of increasing poverty," she told Global Sisters Report. "And now, the risks are enormous in Ukraine because war situations make it easier for international and local gangs to find prey."

Poole is president of Religious in Europe Networking Against Trafficking and Exploitation, or RENATE, a nongovernmental organization that combats human trafficking in 31 European countries.

Millions of Ukrainians have left their homes, fleeing bombings and destruction. In a little over a month of fighting, more than 4 million of them have crossed the borders, mostly into Poland. About as many have been displaced within their country, going west, where the fighting has been less intense. Thousands are waiting in underground shelters, hoping for a ride to safety as soon as possible.

"The situation is dire in shelters," said Sister Poole. "Food is scarce, hygiene is very bad. Such chaos is welcomed by gangs of traffickers, who prey on the most vulnerable: isolated children or young people."

It does not take long for gangs, local as well as international, to mingle in the crowd and offer false promises of help. Traffickers know refugees are desperate to go to a safer place. They are quick to offer a ride over the border to people who are desperate to leave. This is where danger lies.

Soon after the war broke out, humanitarian aid agencies started to distribute leaflets to refugees gathered in shelters, to warn them about human trafficking.

"We have printed and distributed leaflets written both in English and in Ukrainian, so humanitarian workers know what is written on them as well," Sister Poole said.

The paper tells refugees what to do before agreeing to a ride to the border with Poland or Romania, the two main countries where Ukrainians seek refuge, along with Hungary and Slovakia.

"Never hand out your passport to someone who promises you a ride. Take a picture of the plate of the van you get on and tell someone that you are going in it and where you are going" are some of the tips printed on the leaflets.

These leaflets are like an "A to Z guide for refugees of how to protect themselves from transnational gangs," Sister Poole said.

"We try to give cellphones to the ones who do not have one, so they can stay in contact with their relatives," added the nun, who is based in Tirana, Albania, where she has been fighting human trafficking for the past 15 years.

She is coordinating efforts to help refugees, working closely with other helpers within Ukraine, priests and sisters with whom she is in contact.

Sister Poole told Global Sisters Report anyone traveling should register with the authorities when possible.

"The police tell humanitarian agencies in Ukraine that they are very aware of the presence of international gangs of traffickers. They say they patrol the routes taken by refugees to try to prevent criminals from preying on vulnerable people," she added.

Aid workers also watch out for people acting in a suspicious manner and report them to the police.

"Drug trafficking doesn't bring as much money as it used to. Arms trafficking is also not so lucrative anymore, so traffickers are now focusing on human trafficking," she said.

"Children are bought online" she added. "They become sex slaves or forced to work for free."

Even very young children are at risk: "Traffic starts with small children," she said, though "anyone can become a victim of it, not only young boys and girls."

"The world is demanding cheap labor, cheap sex. Traffickers know that wars give them opportunities. Their only aim is greed; they have absolutely no ethics. And criminals often get away with it," she said.

Since the German border is only a six-hour drive from Ukraine, some West Europeans have driven to the border to offer help. This may be generous but also dangerous.

Sister Poole also insists on the need for volunteers to be qualified. "People who help might not be aware of the trauma refugees suffer and of the impact of fleeing a war," she said. "What is needed at this time is a listening ear for these refugees who have suffered so much."

Auvillain is a freelance journalist based in Paris.

This story was originally published in Global Sisters Report, a project of National Catholic Reporter. The website is http://globalsistersreport.org.