Businesses across Wakefield have been visited by police investigating human trafficking in the first operation of its kind in the district.
Detectives and colleagues including immigration officials and the Environment Agency visited a number of businesses employing manual labour across the district last week to speak to employees.
No-one came forward during the operation to say they had been trafficked or exploited but a number of pieces of intelligence were received.
In March the team helped disrupt an organised crime group after arresting and prosecuting a London man who was found guilty of modern slavery offences in the Bradford District.
He was jailed for four years in March and given a ten year Slavery Trafficking Prevention Order.
Chief Inspector Kate Riley of Wakefield District Police said: “Human trafficking and modern slavery are, quite simply, crimes which should not be taking place in the 21st century. The intelligence we gained is being investigated and more operations are planned for the coming months.”