Police have arrested 13 people in an anti-slavery crackdown.
Two men and two women believed to be victims of trafficking were found during raids on eight properties across Newcastle and County Durham.
They have been taken to a safe place and will be supported by other agencies.
Eight men and five women were arrested on suspicion of trafficking people into the UK for exploitation.
Detective Superintendent Steve Barron, of Northumbria Police's Safeguarding Department, said that modern slavery was an increasing problem across Europe.
"This type of crime forces people through threats or coercion to work for little or no pay, or to pay off outstanding debts," he said.
Newcastle City Council leader Nick Forbes said: "Some might find it hard to believe that in the twenty first century we still have slavery, and it is all the more shocking to think that it is happening right here in Newcastle."
The council has set up a reception centre to help victims.
Police released photos of Polish driving licences and a bank card they seized during the operation.
A total of 884 modern slavery crimes were recorded by police in England and Wales over the 2015/16 financial year.