Magnum Photos is reexamining its digital archive of over one million images amid accusations that the agency was promoting and licensing photographs of sexually exploited minors. The allegations were first aired in an article on Fstoppers.com, then spread on social media.

At the center of the controversy is a series of images made in 1989 by American photographer David Alan Harvey that document sex workers in Bangkok and were, until recently, tagged in Magnum’s archive as “teenage girl – 13 to 18 years.” The entire archive has since been taken offline. A spokesperson for Magnum told The Guardian that the agency has not yet determined the accuracy of the tags or who provided them. Artforum has contacted Harvey for comment.

A statement published on Friday by Magnum’s new president, the British photographer Olivia Arthur, said that the cooperative—widely considered the world’s leading photography agency—was made aware of “historical material in our archive that is problematic in terms of imagery, captioning or keywording and we are taking this extremely seriously. We have begun a process of in-depth internal review—with outside guidance—to make sure that we fully understand the implications of the work in the archive, both in terms of imagery and context.”

“Standards for what has been acceptable have evolved,” Arthur continued in her statement. “Issues and questions that were previously overlooked, have to be addressed. That’s a good thing. With this review of the archive we do not want to undo historical work but make sure that we understand the full ethical considerations. Some cases will be clear cut, others will not be easy decisions, full of grey zones.” According to Fstoppers.com, Magnum’s website yielded more than 100 results with the search terms “girl prostitute.”

Arthur’s statement drew rebuke online, where many condemned the use of the word “historical” as a way for Magnum to absolve itself of responsibility for the images in question, many of which flout UNICEF’s guidelines for ethically documenting children. Some critics have urged Magnum—founded on humanist ideals in 1947 by Robert Capa, Henri Cartier-Bresson, George Rodger, and David Seymour—to expand its reckoning to account more broadly for the legacy of the collective, which has faced mounting criticism for facilitating the exploitation of photographed subjects.

Last month, Magnum recruited five new members—including three photographers of color—following complaints about the co-op’s lack of diversity made during this summer’s Black Lives Matter protests, which have lent a new, urgent backdrop to longstanding industry debates over issues of ethics and consent.