Hillary Clinton only learned about the now-infamous "Trump dossier" after BuzzFeed News posted it, despite the fact that the Clinton campaign and the Democratic National Committee helped fund it, a source confirmed to CBS News.

A former British spy, Christopher Steele, complied the explosive allegations in the 35-page dossier for Fusion GPS during the 2016 campaign. In January 2017, BuzzFeed News published the full dossier, though it contained unsubstantiated allegations.

The dossier alleged connections between then-presidential candidate Donald Trump and the Kremlin. Some of the information in the dossier is now under investigation by Special Counsel Robert Mueller. According to the Associated Press, Steele met with investigators earlier this month.

Who funded Trump dossier?

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That Clinton was unaware of the Trump dossier was first reported by The New York Times.

Law firm Perkins Coie, which represented both the Clinton campaign and the Democratic National Committee, and Clinton campaign lawyer Marc E. Elias confirmed Wednesday it had retained the firm Fusion GPS in April 2016 to "perform a variety of research services."

President Trump on Wednesday said the latest developments are a "disgrace."

"Well, I think it's very sad what they've done with this fake dossier," Mr. Trump said. "Hillary Clinton always denied it, the Democrats always denied it."

Top Clinton campaign officials have long denied knowing about the effort to dig up dirt. Former DNC chair Debbie Wasserman Schultz also said she was unaware of the dossier, and Clinton campaign spokesman Brian Fallon tweeted Tuesday that he didn't know about it. Fallon said on CNN that he believed the number of people in the campaign who knew about it was "kept to a small group."

Steve Chaggaris contributed to this report.