Officers acting on warrant searched a number of lock-ups in Glenburn Avenue in the Baillieston area of Glasgow at about 6pm yesterday.
They found a large quantity of drugs, believed to be amphetamine, cocaine and diazepam in one of them.
The drugs have an estimated street value of around £1 million.
Police investigations are continuing.
Detective Inspector Frank Clarke, of Stewart Street CID, said: "This was an intelligence-led operation aimed at targeting those who bring misery to our communities.
"I would urge members of the public to continue to come forward with any information or concerns in their areas."