Cumbria Police are urging publicans to heed government advice, or face prohibition.
Assistant Chief Constable Andrew Slattery said:
"Owners must close their pubs, keep them closed and leave your curtains open to show you are complying.
"Any breach will be subject to prohibition notices, and potentially unlimited fines and may result in loss of your license to sell alcohol.
"Police and local authority staff will be actively checking for compliance across the county."