A spokesman for the special counsel Robert Mueller said "many stories about our investigation have been inaccurate" and advised reporters to "be very cautious."
The office of the special counsel Robert Mueller has said much of the reporting on the investigation into Russian election meddling and the Trump campaign are inaccurate.
A statement warned reporters to "be very cautious" about claims made of the internal workings on Mueller's investigation, which it said resulted in "many" claims that didn't stack up.
News outlets, including Business Insider, routinely report on the progress of the investigation, often citing anonymous sources whose knowledge of the investigation is often unclear to readers.
The practice is a long-standing journalistic convention designed to protect sources from reprisal for speaking out of turn. Mueller's office does not typically give much on-the-record commentary.
But this statement, confirmed by Business Insider, struck a different tone. It was previously reported by The Washington Times, a pro-Trump outlet that routinely takes aim at reports hostile to the president.
The spokesman said:
"What I have been telling all reporters is that many stories about our investigation have been inaccurate.
"Be very cautious about any source that claims to have knowledge about our investigation and dig deep into what they claim before reporting on it.
"If another outlet reports something, don't run with it unless you have your own sourcing to back it up."
Trump has routinely attacked anonymously sourced political reporting, alleging that sources without names attached are often fabricated. For example:
That said, Trump has also promoted anonymously sourced stories that are favorable to him.
And as a New Yorker report from June 2017 illustrated, Trump himself is believed to have a history of serving as an anonymous source, for stories in The National Enquirer.