The find came after neighbourhood police going along Bowling Back Lane in Bradford saw a man run away from a car outside industrial units.
The officers’ search led to the discovery of heroin with a street value said to be more than £1m.
A 28-year-old man arrested in connection with last Friday’s find has now been bailed.
The drugs and related paraphernalia have been forensically examined and investigations were yesterday continuing.
Chief Inspector Damien Miller, of Bradford South police, said: “We are determined to tackle drugs and the crime that is associated with its supply and possession.
“Targeting drug dealing on the streets for instance is one of the local priorities which have been set by the Bowling, Barkerend and Bradford Moor neighbourhood policing team after consultation with community.
“This is complemented by the many proactive operations which have taken place in recent months focusing specifically on these issues.
Inspector Andy Gallant from the neighbourhood policing team said: “In this latest find, the officers used their initiative and intuition to uncover a huge haul of suspected class A drugs.
“We will continue to provide a visible presence in the area, targeting those who aim to threaten our neighbourhoods through criminal activity.”
Anyone with more information is urged to contact the officers.