By Oliver Effron, CNN Business

(CNN) -- A bug in Instagram's algorithm systemically shielded Donald Trump from negative hashtags without doing the same for rival Joe Biden, the company confirmed.

According to an investigation from the Tech Transparency Project, since at least June, searches for Biden-related content returned hashtags with counter-messaging, while searches for Trump-related content did not return any hashtags at all. Instagram has since disabled its 'related hashtags' feature — which algorithmically suggests content relevant to a user's search — calling the discrepancy a "technical error."

Further investigation from Buzzfeed found that until recently, searching for #JoeBiden on Instagram would also return results for #trump2020landslide and #democratsdestroyamerica alongside pro-Biden messaging. Meanwhile, a similar search for #DonaldTrump did not return related hashtags.

Katie Paul, a director of the Tech Transparency Project, told Buzzfeed that the suppression of related hashtags "removes any possibility that negative hashtags could be associated with [Trump'] name or campaign slogans."

An Instagram spokesperson said that the bug — which also affected tens of thousands of nonpolitical hashtags — "appears to have impacted both parties." She noted that some pro-Trump tags, including #trumppence2020 and #votetrump, displayed related hashtags, whereas #democrats did not.

The tags #trumppence2020 and #votetrump are connected to 60,000 and 133,000 posts respectively, whereas #Trump — which did not display related hashtags — has more than 14 million posts.

Tim Murtaugh, the director of communications for the Trump campaign, denied the algorithm had a pro-Trump bias, and expressed unfounded claims that Silicon Valley companies are staffed by "the extreme left." The Biden campaign declined to comment.