The men have been reported acting suspiciously on a string of occasion around the south Shropshire and north Worcestershire area.
A spokesman for West Mercia Police said a licence plate number had been taken for the suspicious vehicle and people were being warned to be on their guard.
He said: " At 11.15am on August 23 a white Ford transit, registration WL07 AJX, was seen paying attention to a farm yard situated around Seifton, Corvedale Road, near Craven Arms.
"This vehicle has been reported as acting suspiciously on other occasions along the Worcestershire border over the past month.
"Previous reports suggest the vehicle usually has three male occupants."
Anyone with information or concerns about criminal activity is asked to call West Mercia Police on 101.