President Donald Trump defended himself in a series of tweets early Tuesday after reports surfaced saying he disclosed highly classified information last week to Russia's Foreign Minister Sergei Lavrov and Ambassador Sergei Kislyak in a White House meeting about a planned Islamic State group (ISIS) operation.

On Monday, the Washington Post reported Trump did not disclose the exact source used for the intel, but he provided “code-word information,” apparently connected to an ISIS plot related to the use of laptops on board passenger aircraft.

Top administration officials however, who attended the meeting, responded to allegations Monday, saying Trump’s meeting with Lavrov consisted only of broad discussions surrounding counter-terrorism.

“During President Trump’s meeting with Foreign Minister Lavrov, a broad range of subjects were discussed, among which were common efforts and threats regarding counter-terrorism,” Rex Tillerson, the secretary of state, said. “During that exchange, the nature of specific threats were discussed, but they did not discuss sources, methods or military operations.”

Read: Can A President Disclose Classified Intel?

The White House also rejected the claims about Trump revealing classified information to Russian officials.

H.R. McMaster, Trump’s national security adviser, said the president and Russian foreign minister “reviewed common threats from terrorist organisations to include threats to aviation.”

"The story that came out tonight as reported is false," Trump's National Security Adviser H.R. McMaster told reporters at the White House Monday. "At no time were intelligence sources or methods discussed. The president did not disclose any military operations that were not already publicly known. I was in the room. It didn't happen."

On Tuesday, a spokesperson for Russia’s foreign ministry denounced the reports as "  yet another fake" story, adding the U.S. media was “not only harmful, but dangerous” and claimed the story was a planned hit against Russia, according to the Associated Press.

Trump drew strong condemnation from Democrats following the Washington Post report while some Republican lawmakers also slammed the president.

Senate Democratic leader Chuck Schumer said the report, if true, was “very disturbing,” while Senate's second-highest ranked Democrat, Dick Durbin, said Trump's actions appeared to be "dangerous" and reckless." 

Bob Corker, the Republican head of the Senate Foreign Relations Committee, also called the allegations "very, very troubling" if true. “Obviously, they’re in a downward spiral right now and they’ve got to come to grips with all that’s happening," he said of the White House.

According to Reuters, one senior NATO diplomat responded to the Washington Post report saying: "If true, this is not going to instil confidence in allies already wary of sharing the most sensitive information."

A spokesman for Paul Ryan, Republican speaker of the House of Representatives, said: "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."

The latest controversy came as Trump's administration continues to recover from backlash over the abrupt removal of former FBI Director James Comey, who was carrying out an investigation into   Russians' meddling in the 2016 presidential election.