These rodents are up to gnaw good.

A shipment of gourmet cured meats meant for a trendy Upper East Side butcher shop was plundered by rats on its trip through the US mail — leaving the store owner and the meat seller complaining that the post office has refused to made good on $800 in loses.

The boxes of purloined provisions — which included fancy meats that sell for as much as $240 per pound — arrived in foul, poop-filled boxes at Six60One on Amsterdam Avenue this summer with a “huge chunk” ripped from the corner.

Workers quickly realized it was the work of the furry fiends.

“It’s disgusting! You can see the hole from the outside and it stinks — inside there’s rat poop and whatever else,” said Jason Felix, the kosher store’s assistant manager.

“I took a picture and sent it to my distributor and said, ‘I can’t sell it like this’ … And I chucked it in the garbage.”

The nasty pictures show that animals, likely rats, scurried inside the box and helped themselves to the variety of gourmet cured meats.

The various vacuum-sealed packages of prosciutto and cured beef — some of which retail for $30 for a 2-ounce package — were torn into and nibbled.

Some packages survived, but were covered in animal feces and risked contamination by being in the same box.

In total, $808 worth of Ben’s Best Charcuterie meat ended up in the trash — and left lots of hungry Upper East Siders unsatisfied.

“The product is so high-end, I cannot keep an inventory. Now we don’t have that inventory, so people were looking for it and I didn’t make money out of it,” explained Felix.

Fortunately for Felix, Ben’s Best refunded their client the total, but were then forced to absorb the losses when USPS declined the company’s insurance claim, CEO Doug Lapin said.

“USPS rejecting a claim is very frustrating. They have not given any valid reason. They are part of the government so cannot be sued … They should pay the claim,” the CEO said.

“On a number of occasions, we have had product stolen out of the boxes, but rats feasting on our meat is a first … The rats have good taste!

It’s not clear when the animals would have scurried into the package, but tracking data shows that it was passed off to five different USPS locations across its four-day journey from Miami to the Upper East Side — including a night at a Midtown distribution center after the mail carrier pushed back its delivery day.

A USPS rep only told The Post it could not find a claim from Ben’s Best Charcuterie regarding the issue.