Officers from the National Crime Agency are carrying out arrests and searches at address across West Yorkshire today (Wednesday).
The NCA are searching addresses in Cleckheaton, Bradford and Dewsbury as part of the operation over money-laundering.
West Yorkshire Police is supporting the operation, which involves multiple arrests.
A spokesman for the NCA said: “Today’s action is pre-planned and being carried out with the support of local police officers.
"The action is against people suspected of being involved in a money laundering group and, as such, residents should not be unduly concerned about public safety during today’s activity.”
The NCA lead investigations and action over serious and organised crime, including large-scale fraud and money-laundering.