By Jeff Mason and Patricia Zengerle
WASHINGTON (Reuters) - President Donald Trump disclosed highly classified information to Russia's foreign minister about a planned Islamic State operation, two U.S. officials said on Monday, plunging the White House into another controversy just months into Trump's short tenure in office.
The intelligence, shared at a meeting last week with Russian Foreign Minister Sergei Lavrov and Russian Ambassador Sergei Kislyak, was supplied by a U.S. ally in the fight against the militant group, both officials with knowledge of the situation said.
The White House declared the allegations, first reported by the Washington Post, incorrect.
"The story that came out tonight as reported is false," H.R. McMaster, Trump's national security adviser, told reporters at the White House, adding that the leaders reviewed a range of common threats including to civil aviation.
"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," he said.
Russia's foreign ministry said reports that Trump had revealed highly classified information were "fake", according to the Interfax news agency.
The White House also released a statement from Secretary of State Rex Tillerson, who said the Oval Office meeting focused on counterterrorism, and from Deputy National Security Adviser Dina Powell, who called the Washington Post story false.
Still, the news triggered concern in Congress.
The Senate's No. 2 Democrat, Dick Durbin, called Trump's conduct "dangerous" and "reckless".
Bob Corker, the Republican head of the Senate Foreign Relations Committee, 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.
The latest controversy came as Trump's administration reels from the fallout over his abrupt dismissal of former FBI Director James Comey and amid congressional calls for an independent investigation into allegations of Russian meddling in the 2016 U.S. election.
One of the officials said the intelligence discussed by Trump in his meeting with Lavrov was classified "Top Secret" and held in a secure "compartment" to which only a handful of intelligence officials have access.
After Trump's disclosure of the information, which one of the officials described as spontaneous, officials immediately called the CIA and the National Security Agency, both of which have agreements with a number of allied intelligence services around the world, and informed them what had happened.
While the president has the authority to disclose even the most highly classified information at will, in this case he did so without consulting the ally that provided it, which threatens to jeopardize a long-standing intelligence-sharing agreement, the U.S. officials said.
Since taking office in January, Trump has careened from controversy to controversy, complaining on the first day about news coverage of his inauguration crowds; charging his predecessor, former President Barack Obama, with wiretapping; and just last week firing the FBI director who was overseeing an investigation into potential ties between Trump's presidential campaign and the Russian government.
Trump, a Republican who has called allegations of links between his campaign team and Russia a "total scam," sharply criticized his 2016 election rival, Democrat Hillary Clinton, for her handling of classified information as secretary of state, when she used a private email server.
The FBI concluded that no criminal charges against Clinton were warranted, but Comey said she and her colleagues had been "careless" with classified information.
In his conversations with the Russian officials, Trump appeared to be boasting about his knowledge of the looming threats, telling them he was briefed on "great intel every day," an official with knowledge of the exchange said, according to the Post.
Some U.S. officials have told Reuters they have been concerned about disclosing highly classified intelligence to Trump.
One official, who requested anonymity to discuss dealing with the president, said last month: "He has no filter; it's in one ear and out the mouth."
One of the officials with knowledge of Trump's meeting with the Russian called the timing of the disclosure "particularly unfortunate," as the President prepares for a White House meeting on Tuesday with Turkish President Tayyip Erdogan, an ally in the fight against Islamic State.
Trump's first foreign trip also begins later this week and includes a stop in Saudi Arabia, another Islamic State foe, and a May 25 NATO meeting in Brussels attended by other important U.S. allies. He also has stops planned in Israel and the Vatican.
The president's trip and latest uproar over his meeting with Russian officials come amid rumors that he might shake-up his senior staff in a bid to refocus his administration.
(Additional reporting by David Alexander, Mark Hosenball, Susan Cornwell, Ayesha Rascoe and Steve Holland; Editing by Kieran Murray and Bill Tarrant, Ralph Boulton)