Officers from the Scottish Crime and Drug Enforcement Agency (SCDEA), in conjunction with Lothian and Borders Police, swooped on a number of addresses in Prestonpans, East Lothian, to uncover the haul.
Police chiefs today said the operation was dedicated to "removing the scourge of drugs from local neighbourhoods".
Drug charities say diazepam is being used as a heroin substitute, while it is often taken alongside alcohol and methadone to ease the comedown from crack cocaine.
On the street it is nicknamed "blues" or "vallies", and a 10mg tablet is available for 1 or less.
Diazepam is smuggled into Scotland from legitimate sources in Europe, while it is also being bought over the internet from India, Pakistan and Thailand.
Detective Superintendent Rikki Bailey, from the SCDEA Investigations unit, said: "Too many of Scotland's communities are affected by the fear, intimidation and violence associated with the illegal drugs trade.
"The continued support of communities through information is also vital to our efforts to dismantle organised crime in Scotland, and I would encourage anyone who has information on drug dealing in their community to report it to their local police."
The latest seizure is among the largest recoveries of diazepam in the Lothians made by law enforcement agencies.
In June, six men were arrested and charged with drug offences after police seized diazepam and cannabis worth 127,000 in a series of searches across the Capital.
The biggest recovery came when officers searched a vehicle at a petrol station in Murrayburn Road in the west of Edinburgh. Diazepam with an estimated street value of 100,000 was discovered.
A police spokesman said: "Lothian and Borders Police is committed to building safer communities across the Force area through a combination of enforcement and prevention and removing the scourge of drugs from our local neighbourhoods is key to helping us achieve this aim."
The rising popularity of diazepam is thought to be down partly to its cheapness and easy availability, along a drop in the availability and quality of heroin.
Two men, aged 34 and 38, were arrested at addresses in Prestonpans in connection with the drug discovery. Both men have been charged with importation offences and offences under the Misuse of Drugs Act, and appeared at Haddington Sheriff Court on Monday.