Officers said a "huge recovery" of what were believed to be controlled substances were recovered in a pre-planned operation in Staffordshire.
Properties in Manchester, Essex and London are also being searched.
The suspects are currently in custody and being questioned on suspicion of conspiracy to supply Class A drugs.
They include four men from London, aged 25, 28, 29 and 56, a 45-year-old man from Northolt, two men from Poland, aged 32 and 48, and a 44-year-old man from the Netherlands.
The raids on Friday evening involved officers from the Titan North West Regional Crime Unit and the National Crime Agency.
Eight men have been arrested on suspicion of drugs offences after three vehicles were stopped on the M6 motorway.