The UK is less effective than Albania and Taiwan at protecting victims of human trafficking, a report has claimed.
Imprisoning victims for immigration offences led to the UK scoring just two out of five in the index measuring the effectiveness of government policies to fight trafficking.
The UK is neglecting its duty to protect victims, the researchers from Germany and the London School of Economics and Political Science said.
Eric Neumayer, of the London School of Economics, said: "There have been great improvements in tackling this horrifying industry, with stricter enforcement and improved co-operation between countries.
"However, many countries, including the UK, are neglecting their duty to adequately protect the victims of trafficking."
The 3P Anti-trafficking Policy Index assessed the policies of 177 countries in terms of prosecution, protection and prevention of trafficking offences between 2000 and 2009.
The worst performer was North Korea with three out of 15.
There have been fears raised in recent months that the Commonwealth Games, due to be held in Glasgow in 2014, could spark an increase in human trafficking and prostitution.