Mr Johnson made the claim at the G7 meeting of world leaders as he called for an easing of US trade restrictions on UK products, but the chairman of the Melton Mowbray Pork Pie Association has said the PM is wrong.
Asked if the PM was correct, Matthew O'Callaghan told BBC Radio 4's Today programme: "Not really. With all of these things, it is a little bit of give and take.
"We don't actually export to Thailand or to Iceland."
"Good for him. I mean, great product, and why not?"
The remarks came after Mr Johnson used pork pies as an example of the need for the US to change restrictions on British products in the American market.
Mr Johnson said on Saturday: "Of course, I think there is a massive opportunity for Britain but we must understand that it is not all going to be plain sailing.
"There remain very considerable barriers in the US to British businesses which are not widely understood.
"Last night, I had my first opportunity to mention some of these to the president...
"Melton Mowbray pork pies, which are sold in Thailand and in Iceland, are currently unable to enter the US market because of, I don't know, some sort of food and drug administration restriction."