The lists allow Google employees –who CEO Sundar Pichai told Congress in December never “manually intervene on any particular search result”– to suppress certain addresses in a user’s search results.

The Daily Caller claims to have seen screenshots of the lists in question. Google did not address whether its staff deliberately weed out certain political content, but did say they are working to filter out “inappropriate” search results.

The first list, titled “webanswers_url_blacklist,” lets staff block specific web addresses from popping up in Google’s ‘featured snippets’ when a user asks a question. Many of the pages blocked are op-ed articles, which a user could mistake for straight news reporting. This list appears to target opinion pieces in general, regardless of their political bent.

Another list, which the Daily Caller suggests was compiled by algorithm, blanket blacklists a host of conservative and “fringe” sites from appearing in the ‘featured snippets.’ The American Spectator, Breitbart, The Gateway Pundit and the website of Bring Your Bible to School Day are among those included. Several progressive sites, including Consortium News and a blog called Breitbart Unmasked also reportedly made the list.

That Google would censor conservative or “fringe” content will come as no surprise to some. The company, along with a bevy of other Silicon Valley tech giants, has been accused of harboring a liberal bias for several years now, with new stories of favoritism surfacing regularly.

A recent study found that Google’s search algorithms display a “left-leaning ideological skew,” while video footage of an internal company meeting recorded after the 2016 election showed executives calling Donald Trump’s victory “deeply offensive” and talking about using AI to fight populism in future.

YouTube, a subsidiary of Google, implemented a blanket ban on “hateful” and “supremacist” videos last week. The ban, which came about after Vox journalist Carlos Maza led a campaign against conservative shock-jock Steven Crowder, swept away or demonetized thousands of videos critical of the social justice movement and several video reports on extremist movements by legitimate journalists.

‘This will not go well’: YouTube cracks down on pundits & journalists after policy change

Though the right has made the most noise about big tech’s alleged censorship efforts, a growing number of left-wing voices have been sounding the alarm too. Facebook has been perhaps most overt in clamping down on anti-establishment content across the political spectrum, but Google has also come under fire for changing its algorithms to de-rank left-wing, socialist, and anti-war websites.

Journalist Max Blumenthal called the tech giants’ clampdown part of “a wider war on dissident narratives in online media.”