The Anti-Defamation League was surprised to find its ads appearing on Breitbart

The Anti-Defamation League has been one of the most outspoken critics of Donald Trump's appointment of Breitbart chairman Stephen Bannon to a top White House post.

So it came as a surprise to the Jewish anti-bigotry group this week when it discovered that it actually numbered among the far-right news site's advertisers.

They weren't the only one. Because many of its digital ads are placed by a third-party network through automated exchanges, the group doesn't have a direct hand in every online ad transaction. The same goes for other advertisers including Kellogg, which also pulled its ads from the website.

The ADL was only alerted to the placements this week after receiving at least one complaint.

ADL spokesman Todd Gutnick said the group immediately put the campaign on hold and cut the ads from the site.

"ADL relies on a third-party vendor to place our advertising online," Gutnick said in a statement. "As soon as we learned that our ads were appearing on the Breitbart website, we paused the campaign and modified our plans. Going forward, ADL ads will no longer appear on that site."

Original image has been replaced. Credit: Mashable

In condemning Bannon's appointment, the ADL has called Breitbart "the premier website of the ‘alt-right,’" which it defines as "a loose-knit group of white nationalists and unabashed anti-Semites and racists."

The agitative site has famously called conservative pundit Bill Kristol a "renegade Jew," and Bannon himself has been accused in court documents of making anti-semitic comments.

Several other advertisers found themselves in a similar position to the ADL this week after an activist's Twitter campaign began publicly notifying major brands that had ads on Breitbart. More than 20 advertisers have scrubbed their ads in response, according to the campaign.

The decision from Kellogg, the most notable of the bunch, triggered a heated response from Breitbart, which called on its readers and supporters to boycott the cereal brand.

The fact that so many brands were caught unaware highlights the incomplete control advertisers have over which sites on which their ads ultimately end up. Even specified blacklists of sites to avoid don't always work, as Digiday notes.