North Korean animators are believed to have worked on programs produced by Japanese and U.S. studios despite sanctions against doing business with the country, a research report released Monday said.

U.S.-based website 38 North, which covers events related to North Korea, said that documents accessed online showed the programs worked on included "Dahliya In Bloom," a Japanese animation series due to air from July and a third season of "Invincible" produced by California-based Skybound Entertainment and to be broadcast on Amazon Prime.

The report said there is no evidence to indicate the studios knew that part of their projects had been outsourced to North Korean animators.

The files discovered from a North Korean internet cloud storage server contained comments and instructions in Chinese, the website run by the Stimson Center, a Washington-based think tank, said, adding that a go-between apparently relayed information between the studios and the animators.

The report said neither the identity of the individual or group that uploaded the files nor that of the involved North Korean partner could be determined, but it said the North Korean entity is likely the April 26 Animation Studio in Pyongyang.

The Pyongyang-based entity is also known as SEK Studio. North Korea has a strong animated film industry, and it was known in the past that SEK Studio and other North Korean animation production companies had earned income by subcontracting for foreign companies.

Other materials identified in the 38 North research included some with the filename "cat," associated with Ekachi Epilka, a Japanese animation studio based in Hokkaido, and video files that appeared to be from "The Octonauts," a BBC children's cartoon.

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