Investigations into suspected VAT fraud and money laundering in the caravan and motor home industry have resulted in five men being arrested.
HM Revenue & Customs (HMRC) officers searched nine premises, seven domestic and two commercial, in Staffordshire, Greater Manchester and Shropshire.
Four men from Staffordshire and one from Greater Manchester were arrested.
They were arrested on suspicion of conspiracy to cheat the public revenue and money laundering offences.
Three of the men arrested on Tuesday morning, aged 36, 37 and 46, are from the Stafford area.
The others are a 45-year-old man from Stone, Staffordshire, and a 67-year-old man from Altrincham, Greater Manchester.
HMRC said it was assisted by Staffordshire and Cheshire police forces.