People who use the drug in public can still be arrested

The giant video screens at Villa Park informed supporters that the drug remains illegal, despite its recent downgrading to Class C.

West Midlands Police saw the match as an ideal opportunity to remind the sell-out 43,000 crowd that cannabis users can be arrested.

The message read: "Whatever you call it, cannabis is still illegal."

Arrest unlikely

Chief Superintendent Bob Baxter said: "The display at Sunday's local derby match is an excellent opportunity for the police and Birmingham Community Safety Partnership to show how we are working together with local communities to reduce crime and disorder.

"In addition, we will use this opportunity to reiterate that cannabis remains an illegal drug."

Police said it was unlikely anyone caught with the drug for the first time would actually face arrest.

Under new guidelines, cannabis users should only be detained in certain aggravating circumstances.

These include smoking in public or using the drug around children, while cannabis users under the age of 17 also face arrest.