Hungarian staff at a pizza franchise in Derby have taken home virtually no pay for months because of illegal deductions, a union claims.
The union claimed to have uncovered several cases
One Domino's delivery driver earned just £5 after four months because accommodation and insurance costs were taken from his pay, the T&G said.
The union alleges it has found at least half a dozen similar cases.
Domino's UK said its own inquiry backed the franchise owner who said he had evidence to disprove the union's claim.
"Both Domino's Pizza and the franchise are fully aware of the procedures to recruit staff and ensure they have the right to work in the UK," the company said in a statement.
The company said some employees had provided statements to its internal investigation which "cast doubt" on a local trade union official's methods and motives.
It said eight employees of the franchise have been dismissed for refusing to comply with the requirement to register on the UK government scheme set up in 2004 for workers from new European Union member states.
The T&G has described it as one of the worst cases of worker exploitation at a leading company in years.
It says that because the workers were always in debt, their situation was a modern form of slavery.
Those who have now been sacked, will also now lose their homes, which were tied to their jobs, the union said.