Officers from North Yorkshire Police arrested two men in their 50s and a woman in her 40s during the operation this morning (January 26).
A police spokesman said they entered a flat in Acomb and found bags of what is believed to be heroin during a search, which have since been sent for forensic analysis.
The operation was led by York outer neighbourhood policing team, supported by specialist search teams, and carried out during neighbourhood policing week, which is a nationwide event to highlight the role of local policing in communities.
They said: “If you have information about drug dealing in your community, tell us by visiting the North Yorkshire Police website, then clicking ‘report’ and reporting a crime.”
You can also contact Crimestoppers anonymously on 0800 555 111.