Wakanda, the fictional homeland of the superhero Black Panther, was briefly listed as an official free trade partner of the United States.

In the Marvel universe the imaginary country can be found in east Africa.

Wakanda appeared in a list of selectable countries on a tariff tracker on the US Department of Agriculture’s (USDA) website.

The error was spotted by Francis Tseng, a software engineer, who tweeted about his discovery on Wednesday.

He posted: “Wakanda is listed as a US free trade partner on the USDA website??”

He later wrote: “fwiw (for what it’s worth) the US would no doubt try to liberalize Wakanda’s markets and flood it with cheap subsidized corn.”

Wakanda appeared in the Marvel comic books before the 2018 movie
Image: Wakanda appeared in the Marvel comic books before the 2018 movie

The error on the website has since been rectified, with a spokesman for the department explaining the addition was made during site testing.

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Mike Illenberg told NBC: “Over the past few weeks, the foreign agricultural service staff who maintain the tariff tracker have been using test files to ensure that the system is running properly.

“The Wakanda information should have been removed after testing and has now been taken down.”

The fictional country burst into the public consciousness after last year’s critically and commercially successful Black Panther movie.

It had previously appeared in Marvel comic books.

In the film, the nation uses advanced technology to keep itself isolated from the rest of the world and boasts the motto “Wakanda forever!”.