Two men from Northern Ireland are expected to appear at Stranraer Sheriff Court on Monday charged with possession of heroin with intent to supply.
The two men, a 41-year-old from Magherafelt, and a 30-year-old from Cookstown, were arrested by Police Scotland officers in Cairnryan on July 2.
They were stopped at the ferry terminal and a quantity of suspected Class A drugs recovered.
Officers from the Police Service of Northern Ireland’s (PSNI) organised crime branch have cooperated with Scottish counterparts.
Searches were also carried out in the Cookstown and Magherafelt areas.
Detective Inspector Tom McClure said: “We are grateful to our colleagues in Police Scotland for making these arrests.
“The PSNI is committed to policing the threat posed by drugs in Northern Ireland and will continue to work with our colleagues in both Police Scotland and elsewhere in relation to detecting those involved in the illegal supply of drugs.”