The vehicle was issued with a fine, having been left illegally on Broad Street, outside Barclays Bank.
West Mercia Police’s Herefordshire division says the van was in place in response to “a specific risk to a location within Hereford”.
“We took a decision based on intelligence to park a police vehicle with CCTV cameras in that location knowing that it was on yellow lines,” said Superintendent Kevin Purcell.
“The risk was averted, with the vehicle remaining there for the minimum time necessary.
“Parking on yellow lines is not something that I would usually condone, however I am satisfied that on this occasion the people of Herefordshire would support, and indeed expect, our officers to protect them using appropriate means.
“It is however pleasing to note that our parking enforcement colleagues from Herefordshire Council perform their role without favour or affection and treat every vehicle the same.”
He added he would be appealing the ticket “based on the exact circumstances of the incident”.