The city of Berlin has warned Ukrainian refugees not to accept offers of money or accommodation at the main train station due to concerns that they might be lured into forced prostitution or other forms of human trafficking.
"Please note that there may be criminals on the move at Berlin central station who want to profit from the situation of war refugees," the Berlin government said on the website it has set up for refugees from Ukraine.
Police signs in German, Ukrainian and Russian are displayed at the station, warning women and young people travelling alone to not accept suspicious offers of help.
There was no any concrete evidence so far of refugees being tricked into forced prostitution or kept against their will, a police spokesperson said.
When the first refugees started arriving from Ukraine earlier this month, many Germans flocked to the train station to invite them to their homes. The interior ministry said 300,000 private homes were offered nationwide by last Thursday.
But the authorities are now advising people with a spare room to register their help on coordinated websites instead of approaching refugees on arrival.
Dozens of volunteers saying which languages they speak are helping at the station, recalling scenes from 2015, when more than a million people from the Middle East fled to Europe and Germany took in the bulk of newcomers.
The police, who have increased the number of officers on duty at the station, including those undercover, are asking volunteers to report any suspicious people offering money to host women and children.
International humanitarian organisations like World Vision have warned that the war in Ukraine risks increasing the chances of human trafficking.
"The number of women who are at risk of traffickers capitalising on their vulnerabilities is growing exponentially. This could be done through fraudulent travel and/or employment arrangements," said World Vision Middle East and Eastern Europe Regional Leader Eleanor Monbiot.
(Reporting by Emma Thomasson; Editing by Angus MacSwan)