I downloaded this from the homepage of AIC's website many years ago, but this phone card that says it was from June 2002 is the only evidence I can provide to support that:
https://www.suruga-ya.jp/kaitori/kaitori_detail/978062476
I suppose that qualifies it as official art. Internet Archive has a capture of the page it appeared on, which identifies the artist as Matsumoto Fumio, but the image itself wasn't saved:
https://web.archive.org/web/20020802121159/http://www.anime-int.com:80/info/tereka/index.html
However, the filename of the broken image is wall200206.jpg, so it probably was this image.