People smuggling raids: Arrests made in the North East and south of England
The National Crime Agency (NCA) said 350 officers were involved in the raids in the Northumbria, Cleveland, Sussex and Metropolitan Police force areas.
It said a number of arrests had been made at about 20 addresses.
The gang is suspected of charging up to £10,000 per head to smuggle migrants across the Channel.
The operation followed a year-long investigation with links to the French, Belgian and Dutch authorities, the NCA said.
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.