HMRC has seized £1.5m in cash and made 13 arrests as part of a national operation targeting suspected money laundering.
Two women and 11 men aged between 20 and 54 years-old were arrested across London, Bedfordshire, Wiltshire, Kent, County Armagh and Deeside on suspicion of laundering millions of pounds.
In addition to the arrests, HMRC's 150 officers seized high value cars worth approximately £400,000 and were able to freeze nine bank accounts making up a total of £520,000.
The investigation was part of HMRC’s broader efforts to tackle money laundering in the UK.
Last week HMRC and the Metropolitan Police Service cracked down together on laundering through the regulated sector in London.
Simon York, fraud investigation director at HMRC, 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 £192m of illicit proceeds using its civil and criminal proceeds of crime powers."
Those arrested have been questioned by HMRC and been released pending further enquiries.
HMRC confirmed that its investigations are ongoing.