President Donald Trump revealed highly-classified intelligence about the Islamic State during a White House meeting with two Russian officials last week, according to the Washington Post.

The Post reported Monday night that the information, allegedly discussed with Russian Foreign Minister Sergei Lavrov and ambassador Sergey Kislyak, “had been provided by a U.S. partner through an intelligence-sharing arrangement considered so sensitive that details have been withheld from allies and tightly restricted even within the U.S. government.”

Two U.S. officials familiar with the meeting last week also confirmed the story to Buzzfeed News. Reuters tweeted it had also confirmed the report.

Trump had not been authorized to share with Russia the information gathered through that arrangement, the Post reported, risking the country’s relationship with a key ally in the fight against ISIS.

Washington Post reporter Greg Jaffe, who helped break the story, told PBS NewsHour’s Judy Woodruff that Trump was describing the security threats posed by the use of laptops on airplanes when he began “boasting about the great intel he had, and in doing so, may have overstepped,” sharing details about a terrorist threat from the Islamic State, according to his sources.

The White House has not responded to NewsHour’s request for comment.

"I think the ally…would be upset to have learned that [sensitive info it shared] landed in the Russians' hands," @GregJaffe says #PBSNews pic.twitter.com/MWipXngOWT — PBS NewsHour (@NewsHour) May 15, 2017

National Security Adviser H.R. McMaster told the Associated Press that “no intelligence sources or methods were discussed and no military operations were disclosed that were not already known publicly.” Secretary of State Rex Tillerson also told Reuters that Trump did not discuss “sources, methods or military operations.”

Later, in a brief statement outside the White House, McMaster said “I was in the room. It didn’t happen.”

"I was in the room – it didn't happen," says Natl Sec Advisor McMaster of report Pres Trump disclosed higly classified info to the Russians. pic.twitter.com/mVQceZsjUd — Mark Knoller (@markknoller) May 15, 2017

Trump’s meeting with Lavrov and Kislyak drew criticism last week for its exclusion of U.S. press as well as its timing the day after FBI director James Comey’s firing. The timing of Comey’s firing — as he led an investigation into Russia’s interference in the 2016 elections and possible ties to Trump’s campaign — concerned Democrats and some Republicans. In the aftermath, some lawmakers have called for an independent counsel to launch a new investigation. The concerns were amplified on Thursday, after Trump’s interview with NBC’s Lester Holt, in which he said he was going to fire Comey “regardless of recommendations.”

READ MORE: Everything we know about Trump’s firing of FBI director James Comey

“And in fact, when I decided to just do it, I said to myself — I said, you know, this Russia thing with Trump and Russia is a made-up story. It’s an excuse by the Democrats for having lost an election that they should’ve won,” he added.

House Speaker Paul Ryan said in a statement “we have no way to know what was said, but protecting our nation’s secrets is paramount. The speaker hopes for a full explanation of the facts from the administration.”

Sen. Mark Warner, D-Va, tweeted that the story, if true, “is a slap in the face to the intel community. Risking sources & methods is inexcusable, particularly with the Russians.”