Raids have taken place across England in an operation to tackle people smuggling involving suspected Kurdish gangsters.
The National Crime Agency (NCA) said 350 officers were involved in the raids in Middlesbrough, Hartlepool, Stockton, Newcastle, Hastings and London.
Officers raided about 20 addresses and arrested 20 men and one woman.
The gang is suspected of charging up to £10,000 per head to smuggle migrants in the back of lorries across the Channel.
As well as residential properties, a number of car washes believed to be linked to money laundering activities were also raided.
The NCA said most of the trafficked immigrants are Iraqi Kurds and mostly men, but some families have also been brought into Britain.
Deputy director Tom Dowdall said: "We believe we have identified and disrupted a significant network which is suspected of smuggling hundreds of migrants into the UK and planned to carry on going."
Police arrested a 42-year-old from a terraced house in Devonshire Road, Linthorpe, Middlesbrough, who was one of 16 people arrested in the Cleveland Police area.
A further two people were arrested in London, as well as two in Sussex and one in the Northumbria area.
The NCA's senior investigating officer Mark Spoors said the suspects were arrested on suspicion of immigration offences and linked to money laundering.
"The crime group have used complicit lorry drivers running from France into the UK," he added.
Mr Spoors said the operation had been a success as all the targets had been arrested.
The operation followed a year-long investigation with links to the French, Belgian and Dutch authorities, the NCA said.
It said it was one of the biggest operations it had carried out since it started five years ago.
Officers at a briefing at Cleveland Police's HQ in Middlesbrough were told some of those targeted were suspected of being involved in bringing migrants into the UK in lorries for money.
They were told two men in the Linthorpe area of Middlesbrough were thought to be ringleaders.