Graham said: “Parking in a supermarket car park when the store is closed sounds completely fine on the face of it.
“But it can actually lead to a fine of up to £100, and we’ve seen cases where people have been clobbered for leaving their car for a matter of minutes.
“Check the signage as you enter the car park carefully before making a decision about whether to stay or not.
“Not all store car parks enforce after-hours restrictions, but many do, and it’s causing real confusion among motorists.”
Supermarkets are often built on private land with enforcement companies usually in charge of monitoring parking.
Many have ANPR cameras installed and will detect number plates if they are on-site after hours.
Vehicle owners will likely not be aware they have been snapped by detectors until a fine arrives in the post days later.
Penalties can start as low as £40 but some may be up to £100 in a blow for cash-strapped individuals.
Tesco, Sainsbury’s, Asda, Morrisons and Waitrose all explained that the exact terms of conditions of parking will vary between stores.
However, most supermarkets stressed that road users should be able to find all the necessary details clearly signposted.
This should clearly outline any restrictions which will include any time limits on each stay and the car park’s operating hours.
Conway added: “A supermarket car park is provided so that you can use the store in the most convenient manner possible.
“While it sounds harsh and punitive, it makes sense that car parking fines could be levied if the shop itself is closed.”