Efforts to fight the global problem of human trafficking are being hampered by lack of reliable data, according to a report by a United Nations agency.
Sexual exploitation accounts for nearly 90% of cases
Millions of mainly women victims are trafficked - the vast majority for sex, some for forced labour.
The Office on Drugs and Crime (UNODC) called on countries to face up to a truly worldwide problem.
"The fact this form of slavery still exists in the 21st century shames us all," said the UNODC's director.
Antonio Maria Costa said that efforts to counter trafficking had so far been uncoordinated and inefficient.
"The lack of systematic reporting by authorities is a real problem," he added.
"Governments need to try harder."
The UNODC identified 127 nations, mainly in Africa and Eastern Europe, as sources of trafficking victims, and 137 as destinations.
Among destinations are the European Union, North America, the Gulf states, Israel, Turkey, China and Japan.
Other findings include:
- Women are involved in 77% of trafficking cases
- Children are involved in 33% of cases and just 9% involve men
- Sexual exploitation is a factor in 87% of cases and forced labour is a factor in 28% of cases.