Reddit has become the latest social network to admit that it was infiltrated by Russian misinformation actors in the run-up to the 2016 US election.

In a post on the social news site, Reddit’s chief executive Steve Huffman said that the company has “found and removed a few hundred accounts” which it suspects are of Russian origin, or which were linking directly to “known propaganda domains”.

“The vast majority of suspicious accounts we have found in the past months were banned back in 2015–2016 through our enhanced efforts to prevent abuse of the site generally,” Huffman added.

Reddit has been silent on Russian misinformation efforts on its site for months, despite being viewed as a likely target as far back as September 2017, when the US senator Mark Warner suggested that an investigation into Russian misinformation should expand beyond the initial focus on Twitter and Facebook.

The company appears to have been prompted to speak by a leak from the Internet Research Agency, a notorious “troll farm” which was behind many of the misinformation efforts to date. The documents, seen by the Daily Beast, showed that the agency was sharing “American proxies” for accessing Reddit, and that content from websites it created were receiving “hundreds – and sometimes thousands – [of] upvotes on” Trump-supporting subreddits.

The Daily Beast also reported that at least 21 accounts on Tumblr, the hybrid social network/blogging service owned by Oath (formerly Yahoo), were run directly by the Internet Research Agency.

In his post on Reddit, Huffman acknowledged Reddit’s previous silence on the issue. “While I know it’s frustrating that we don’t share everything we know publicly, I want to reiterate that we take these matters very seriously, and we are co-operating with congressional inquiries. We are growing more sophisticated by the day, and we remain open to suggestions and feedback for how we can improve.”

A parallel investigation into Russian misinformation efforts around the EU referendum has been less fruitful. Little hard evidence of substantial involvement has been uncovered, with technology companies arguing the lack of evidence is proof of a lack of meddling, and other observers querying whether the companies are looking in the right place at all.