The special counsel investigating Russian interference in the 2016 election disputed on Friday a report that said President Trump had directed Michael D. Cohen, his longtime lawyer and fixer, to lie to Congress about his role in negotiations to build a skyscraper in Moscow.

The rare public statement by a spokesman for the special counsel, Robert S. Mueller III, challenged the facts of an article published by BuzzFeed News on Thursday saying that Cohen had told prosecutors about being pressured by the President before his congressional testimony.

“BuzzFeed’s description of specific statements to the special counsel’s office, and characterisation of documents and testimony obtained by this office, regarding Michael Cohen’s congressional testimony are not accurate,” said the spokesman, Peter Carr.

Before Carr’s statement, the BuzzFeed report led to a flurry of reactions by senior members of Congress who said that the allegations, if true, could be grounds for initiating impeachment proceedings against Trump.

The President himself responded on Twitter late on Friday, calling the special counsel’s statement “a very sad day for journalism, but a great day for our Country!”

A proven effort by Trump to pressure a witness to commit perjury would be one of the most damning revelations so far in the investigation into Russia’s attempts to sabotage the 2016 presidential election and could be the cornerstone of a case that the President obstructed justice to keep investigators at bay.

Both the White House and lawyers for Trump vigorously denied the BuzzFeed report even before the special counsel’s office weighed in.

“Two words sum it up better than anything anybody else can say, and that is ‘categorically false,’” the White House press secretary, Sarah Huckabee Sanders, told reporters on Friday.

BuzzFeed News maintained that its report was accurate, its editor, Ben Smith, said after Mueller’s office disputed the account. “We stand by our reporting and the sources who informed it, and we urge the Special Counsel to make clear what he’s disputing,” Smith said on Twitter.

The statement by Carr, the special counsel’s spokesman, was unusual because it appeared to be the first time he had publicly challenged the facts of a news media account that had generated significant attention for its revelations about the President.

The New York Times has not independently confirmed the BuzzFeed report.

One person familiar with Cohen’s testimony to the special counsel’s prosecutors said that Cohen did not state that the President had pressured him to lie to Congress.

Representative Adam B. Schiff, Democrat of California and chairman of the House Intelligence Committee, said that his panel would investigate the BuzzFeed report and was “already working to secure additional witness testimony and documents related to the Trump Tower Moscow deal and other investigative matters.”

If true, Schiff said, the allegations “would constitute both the subornation of perjury as well as obstruction of justice.”

Senator Mark Warner of Virginia, the top Democrat on the Senate Intelligence Committee, told reporters on Friday that the panel expected Cohen to be back to testify privately in early February.

The report added another jolt to a chaotic week for the White House, which has had to fend off questions about recent revelations that FBI counterintelligence agents began investigating Trump in 2017 and that Trump has tried to conceal the details from senior administration officials about his interactions with President Vladimir V. Putin of Russia.