A London-based online content watchdog financed in part by the U.S. Department of State is under fire from conservatives who say the platform consistently flags right-leaning news websites as problematic in an effort to cut off their advertising revenue and “defund disinformation.”

The Global Disinformation Index, founded in 2018, included a number of conservative American websites on its list of “risky” outlets that should be avoided by advertisers. Among them are the American Spectator, the Federalist, the Daily Wire, RealClearPolitics, the libertarian Reason magazine, the New York Post, and the Washington Examiner, which first reported on the group’s activities.

Websites called “least risky” by the group include a litany of progressive-leaning outlets such as ProPublica, National Public Radio, HuffPost, Buzzfeed News, and the Washington Post, among others.

The efforts by the London firm appear to have had the desired effect. A billion-dollar online advertising company owned by Microsoft, Xandr, until recently subscribed to the company’s services and routinely blocked advertising to a number of right-leaning websites, according to the Examiner, including Sean Hannity’s hannity.com, the Washington Times, and rushlimbaugh.com.

Many of the sites were described as “false/misleading” by Global Disinformation’s analysts. Other pejoratives used by the firm’s analysts to describe websites it found offensive include “morally reprehensible or patently offensive” or lacking in “redeeming social value.”

Over the weekend, Microsoft told the Examiner that it was suspending its relationship with the firm and would no longer use its ratings pending an internal review of the questions raised by the Washington Examiner.

The Department of State’s role in financing the activities of the Global Disinformation Index has drawn the ire not only of First Amendment advocates but of some Republicans in Congress. The center was on the receiving end of at least $330,000 from two branches of the Department of State, the Global Engagement Center and the National Endowment for Democracy.

“The State Department should not be funding woke organizations who seek to censor and demonetize conservative outlets,” Representative Elise Stefanik of New York, a Republican who sits on the board of the National Endowment for Democracy, told the Examiner. “House Republicans will assert our oversight over the State Department’s funding of these types of groups.”

Founders of the Global Disinformation Index include a former MTV executive in Europe, Clare Melford, and a professor at New York University’s Center for Global Affairs and a security fellow at the Truman National Security Project, Daniel Rogers.

In their mission statement, the founders said the firm’s founding principal is that most so-called disinformation is promulgated for financial gain and their goal is to cut off funding to the offending sites.

The group defines “disinformation” as narratives that are “adversarial” to democratic institutions, scientific consensus, or at-risk groups. “Adversarial narratives undermine trust in our social, political, economic, and scientific institutions and sow or exacerbate division within our societies, often leading to real world harms, including violence, illness and death,” the group says.

Among the “adversarial narratives” cited by Ms. Melford are “climate change denial” and skepticism about vaccines.