Police have seized half a million prescription pills worth £250,000 which were being posted to the US.
Last week, an investigation was launched into a suspected drugs conspiracy after officers received information about a number of packages left at a courier office.
The boxes were addressed for a shipment to the United States but postal staff grew suspicious of the numerous deliveries and contacted police.
One of the boxes was opened and thousands of alprazolam pills, better known by their brand name Xanax, were found concealed inside.
The sender of the boxes, a 25-year-old man, was immediately traced and arrested and a raid was carried out a property on Stanton Street in the west end of Newcastle.
A search of the property saw huge quantities of pills, a large press machine, thousands of self-seal bags and a grinding machine seized by police.
Police said a man was arrested.
Two other men both aged 23 were also arrested in connection with the investigation and all three have since been released under investigation.
A spokesperson for Northumbria Police said: "Anyone who wants to report suspicious behaviour, or has information about suspected drug dealing, can do so online at the Northumbria Police website.
"You can also call police on 101 or contact independent charity Crimestoppers anonymously on 0800 555 111."
