The firm run by an ex-British spy and the author of the controversial dossier that was used to obtain surveillance warrants against a former Trump campaign official accused President Trump of making "false claims" about them while also standing behind the reporting in the spy's much-panned dossier.

"Yesterday @realDonaldTrump made false claims about us," Orbis Business Intelligence, which is run by former British spy Christopher Steele, said in a tweet. "He wildly exaggerated our fees and, contrary to his claims we have never stated any of our reporting is 'fake'. [sic] We stand by the integrity of our research on Kremlin interference in the 2016 election and support for Trump."

The Steele dossier, which was financed by the Hillary Clinton campaign and the Democratic Party through the American firm Fusion GPS, contains a variety of damning but unverified allegations against the president and served as a basis for Foreign Intelligence Surveillance Act (FISA) warrants against Trump campaign official Carter Page. A Department of Justice Inspector General (OIG) report released in December revealed that the FBI improperly relied on the allegations in the dossier without corroboration when obtaining warrants against Page.

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Orbis was responding to comments Trump made Thursday in the White House's East Room during wide-ranging, off-the-cuff remarks that amounted to a victory lap in the wake of his acquittal on two articles of impeachment earlier this week.

"And by the way, Hillary Clinton and the DNC paid for millions, millions of dollars, the fake dossier," Trump said. "And now Christopher Steele admits that it's a fake because he got sued by rich people. I should have sued him, too but when you're president, people don't like suing."

Steele had previously been sued by a Russian businessman for the allegations in his dossier. Trump was likely referring to revelations from last year that Steele said he included in the dossier unverified information from a now-defunct online source called CNN iReport, which allowed users to submit information and stories that were not fact-checked.

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Orbis, which had previously been silent on the Steele dossier, also made a statement on behalf of itself and Steele in December disputing information included in the OIG report, helmed by Inspector General Michael Horowitz.

"At the twelfth hour late Sunday evening, Orbis was informed by the OIG that previously redacted material had been unredacted and that it contained negative information about Christopher Steele. Orbis was given no opportunity to review, much less comment, on the material," the statement read.

"The result is that the OIG Report contains several serious errors and misstatements that require this response."

Fox News' Brooke Singman and Lukas Mikelionis contributed to this report.