Investigators have seized £1.5 million in cash and arrested 13 people in a series of raids against money laundering.
A team of 150 officers from HM Revenue and Customs (HMRC) carried out warrants in London, Bedfordshire, Wiltshire, Kent, County Armagh and Deeside, and arrested 11 men and two women.
They also confiscated four cars worth a total of around £400,000 and secured nine orders to freeze £520,000 in bank accounts.
Fraud Investigation Director Simon York said: "Money laundering and the organised crime it supports is hugely harmful to businesses, citizens and society as a whole.
"That is why it is a priority for HMRC, and this large-scale operation demonstrates we will not hesitate to investigate those suspected of being involved.
"We are determined to cut off the funds that are the lifeblood of serious crime in the UK and, in the last year alone, HMRC has recovered more than £192 million of illicit proceeds using its civil and criminal proceeds of crime powers."
The 13 arrested in the raids on June 26 have all been released under investigation.
- In Bedfordshire, a 37-year-old man and a 31-year-old woman from two addresses in Bedford, a 54-year-old man from Flitwick, and a 20-year-old woman from Dunstable.
- In London, a 47-year-old man from north Finchley, a 54-year-old man from Southgate, a 51-year-old man from Queens Park, and a 42-year-old man from Hackney.
- In Kent, a 34-year-old man from Beckenham and a 35-year-old man from Ashford.
- The remaining three are a 27-year-old man from Swindon, Wiltshire, a 47-year-old man from Shotton, Deeside, and a 38-year-old man from County Armagh.
Last week, HMRC also carried out action with the Metropolitan Police targeting money service bureaus in the capital suspected of laundering criminal cash.
Around £100 billion of criminal money per year is laundered through the UK.