Six people have been arrested in dawn raids by officers investigating a suspected £20m VAT missing trader and money laundering fraud.
The arrests were made in Angus and Aberdeenshire
Codenamed Operation Vaulter, the action was the result of a 24-month long inquiry.
HM Revenue and Customs officials detained three men and two women in Forfar and one man in Turriff.
Those arrested are being questioned by HMRC investigators at police stations in England.
Searches were carried out at three homes and one commercial premises in an operation assisted by Tayside and Grampian police.
Missing trader VAT fraud involves buying goods free from the tax in another European Union country, selling it at a VAT included priced in the UK, but then disappearing without paying the VAT due to Revenue and Customs.
The goods most commonly associated with the fraud are mobile phones and computer chips.
Chris Harrison, director of operations, criminal investigations, for HM Revenue and Customs said: "Tackling missing trader fraud is HMRC's top priority.
"Today's arrests are the result of a lengthy investigation by dedicated officers who work tirelessly and diligently, fighting criminal attacks on the tax system.
"The sophistication of the organised crime gangs behind these frauds means that our investigations are increasingly complex but we are committed to bringing the criminals responsible to justice and to recovering the money stolen from the British taxpayer, wherever in the world our investigations lead."