Police forces across north Wales, Merseyside and Scotland have launched a series of dawn raids targeting “county lines” drugs gangs.
Operation Tide focused on illegal supplies of heroin and crack cocaine.
Searches were carried out at 24 properties at 07:15 BST in Flintshire, Conwy, and Anglesey in north Wales, and in Liverpool and Scotland.
North Wales Police said more than 300 officers from three forces have taken part in the operation.
Earlier this year, the National Crime Agency estimated 100 county lines drugs networks were operating in Wales.
“Distribution of controlled drugs will not be tolerated and we will continue to take positive robust action. However we can’t tackle this alone and key to all our work is intelligence,” said Supt Mark Pierce, from the north Wales force.