Facebook did not add labels to half of posts pushing content from top climate change deniers, according to an analysis from the Center for Countering Digital Hate.

The research, released on Wednesday, also follows news that lawyers for Facebook whistleblower Frances Haugen have filed a new complaint with the U.S. Securities and Exchange Commission this month claiming the company misled investors about its efforts to tackle climate change and COVID-19 misinformation.

Facebook, now known as Meta Platforms FB.O , has long been under scrutiny over the spread of misinformation on its platforms. The company said last year it would add informational labels to some posts about climate change, to direct users to its new Climate Science Information Center hub.

The UK-based Center for Countering Digital Hate (CCDH) in a report last November identified a list of 10 digital publishers whose articles it said accounted for about 69% of Facebook interactions with climate denial articles, dubbed the "Toxic Ten."

This week, CCDH said that in an analysis of 184 posts pushing articles featuring climate denial content from these publishers, 50.5% of posts did not have information labels.

CCDH said it had analyzed posts published between May 2021 and January 2022, after Meta announced its labeling feature had been rolled out to a number of countries including the United States.

"During the time frame of this report, we hadn't completely rolled out our labeling program, which very likely impacted the results," said Meta spokesman Kevin McAlister. Meta said the initial phase of its labeling effort was only directed at posts seen by a small subset of users.

However, between Dec. 20 and Jan. 20, five out of 12 posts analyzed by CCDH did not have a label.

Meta said it combats climate change misinformation by "connecting people to reliable information in many languages from leading organizations through our Climate Science Center" and also working with independent fact-checkers (of which Reuters is one) to rate content for veracity and accordingly label and reduce its distribution.

One example of an unlabeled post highlighted by CCDH was a NewsBusters article that talked about "alarmist climate propaganda." NewsBusters did not immediately respond to requests for comment.

"Meta keeps claiming it cares about climate change, but they have failed to stop the spread of misinformation about climate change on their platform," said CCDH Chief Executive Imran Ahmed in a statement.

The CCDH also said it wants Meta to release data on the effectiveness of its labels.

A new SEC complaint filed by Whistleblower Aid, first reported by the Washington Post, recently alleged that Facebook misled investors about its work to deal with climate misinformation.

It cited leaked discussions on Facebook's internal message board that said awareness of its Climate Science Information Center was "very low" for users in western markets or that questioned the transparency around decisions over climate change misinformation. It also referenced leaked discussions which showed staff sparring over how the company should handle climate misinformation and flagging "prominent" instances of it on the platform. 

"There are no one-size-fits-all solutions to stopping the spread of misinformation, but we're committed to building new tools and policies to combat it," said Meta spokesperson McAlister in a statement.

(Reporting by Elizabeth Culliford in New York; Editing by Lisa Shumaker) ((elizabeth.culliford@thomsonreuters.com; 2127679959;))