The office of Special Prosecutor Robert Mueller told reporters that "many" stories about his investigation "have been inaccurate."
It was an unusual piece of pushback from an office that tends to keep quiet.
The progress of Mueller's probe into potential Russia-Trump collusion is a source of fascination for many outlets.
Many stories are based on leaks from anonymous figures said to have knowledge of the probe, which are inherently difficult to verify.
The office of Special Prosecutor Robert Mueller has warned that much of the reporting on his investigation into links between the Trump campaign and Russia are inaccurate.
A statement warned reporters to "be very cautious" about claims made of the internal workings on Mueller's probe, which have resulted in "many" claims which don't stack up.
Outlets, including Business Insider, routinely report on the progress of the probe, often citing anonymous sources whose knowledge of the investigation itself is unclear.
The practice is a long-standing journalistic convention which protects sources from reprisal for speaking out of turn. Mueller's office does not typically give much on-the-record commentary of its own.
However this statement, given to The Washington Times, a pro-Trump outlet which routinely takes aim at reports hostile to the President, struck a different tone.
People reportedly interviewed in Mueller's probe:
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:
....it is very possible that those sources don't exist but are made up by fake news writers. #FakeNews is the enemy!
— Donald J. Trump (@realDonaldTrump) May 28, 2017
The Washington Post is far more fiction than fact. Story after story is made up garbage - more like a poorly written novel than good reporting. Always quoting sources (not names), many of which don’t exist. Story on John Kelly isn’t true, just another hit job!
— Donald J. Trump (@realDonaldTrump) April 8, 2018
That said, the President has also promoted anonymously-sourced stories which are favorable to him.
And a New Yorker report from June 2017 alleged that Trump himself was once an anonymous source, for stories in The National Enquirer.