"In general pest infestations are of greatest concern and likely to lead to a poor grade, when they are found in food preparation or food storage areas," Mervyn Chetty, Auckland Council manager environmental health, told Newshub following inspections last year.

"Food outlets should follow their food control plan, which provides information and procedures to ensure regular checks for pests or conditions that may give rise to pests, and take the appropriate action where they find any signs or indications of pests or conditions favourable to pests."

What do the grades mean?

"A D-grade means that faults that are not a critical risk to food safety were found on the premises and intervention by a food safety officer was required," a council spokesperson says.

"E-grades are issued to businesses with critical food safety risks. When a critical risk to food safety is found, the business will immediately close and will reopen when the critical food safety risk has been addressed.

"For example, if a food business is found to have extensive cockroach infestation, it will not be permitted to reopen, unless the cockroach infestation has been satisfactorily mitigated."