Kazbar Bar and Grill closed its kitchen voluntarily after spotting the baby rat in the storeroom, which inspectors confirmed was "an imminent risk to the safety of members of the public consuming food produced."
A food hygiene inspection on October 5, carried out on the same day the rat was found, also discovered droppings in the storeroom, with some found on a net sack containing onions.
The inspector said: "Due to a rat running into the rear storeroom, and the physical presence of droppings suggesting the rat had made a habit of running into the food storeroom, you decided to voluntarily close the kitchen on October 5 2021, until the matter had been resolved.
"After pest proofing works, cleaning, and treatment the kitchen was considered free from pest activity and opened to trade on October 8 2021.
"As mentioned, due to the rat activity your star rating is very low. I appreciate you have carried out work and have now rectified this matter.
"Unfortunately, the star rating is assessed on the day of the unannounced inspection."
The rat had gained entry into the premises through a door with a 2cm gap around the sides, but was fitted with metal plates on October 5 to stop further vermin entry.
Pest proofing was also carried out on a door leading into the beer garden.
The inspector also flagged concerns about a build up of debris in areas where food was handled, prepared, and stored, and these areas were subsequently deep cleaned while the premises was closed.
A sink provided for staff preparing food also did not provide hot water, meaning it did not meet the requirements for hand washing basins.
Water pooling around the wash-up sink, which potentially accumulated due to leaking pipework or a leaning roof, was raised as a concern as a potential breeding ground for bacteria.
Food was also being stored alongside tools and DIY equipment, but was rectified while the premises was closed.
Kazbar Bar and Grill has been contacted for comment.