Modern slavery and human trafficking in the UK is "far more prevalent than previously thought," the National Crime Agency has said.
The NCA said there were more than 300 live policing operations currently, with cases affecting "every large town and city in the country".
The agency estimated that there were tens of thousands of victims.
It said previous estimates of 10,000-13,000 victims in the UK were found to be the "tip of the iceberg".
"The more we look, the more we find," the NCA's vulnerabilities director Will Kerr said.
Mr Kerr said he had been shocked by what he had seen during this year's intensive efforts to break up gangs, with almost every major operation triggering even more investigations.
He warned that trafficking into modern slavery was now so widespread that ordinary people would be unwittingly coming into contact with victims every day.
'Recognise concerns'