WASHINGTON -- The tempest over U.S. President Donald Trump's congratulatory phone call to Vladimir Putin quickly grew on Wednesday into an uproar over White House leaks, sparking an internal investigation and speculation over who might be the next person Trump forces out of the West Wing.

The White House, which has suffered frequent leaks -- at times of notable severity -- said in a statement it would be a "fireable offence and likely illegal" to leak Trump's briefing papers to the press, after word emerged that the president had been warned in briefing materials not to congratulate the Russian president on his re-election.

Trump did so anyway, and on Wednesday he defended the call, saying George W. Bush did not have the "smarts" to work with Putin, and that Barack Obama and his secretary of state, Hillary Clinton "didn't have the energy or chemistry" with the Russian leader.

Aides had included guidance in Trump's talking points for the call to Putin stating: "DO NOT CONGRATULATE," a senior administration official said Wednesday, speaking to The Associated Press on condition of anonymity because the official had not been authorized to discuss internal matters.

The document had been accessible only to a select group of staffers, two officials said, and had been drafted by aides to National Security Adviser H.R. McMaster. They also said there now is an internal probe of the leak but provided no other details. The officials spoke on the condition of anonymity to discuss sensitive internal deliberations. The White House is not formally acknowledging the veracity of the presidential guidance first reported by The Washington Post.

Trump defended his decision to congratulate Putin in his Wednesday tweets, saying Obama did the same in 2012.

"Getting along with Russia (and others) is a good thing, not a bad thing," Trump said, adding that Russia can "help solve problems" from North Korea to "the coming Arms Race."

The White House statement earlier Wednesday about a possible firing was an unusual threat and an indication of the seriousness with which the administration is treating the latest breach. Trump and Chief of Staff John Kelly are both angry over the disclosure, officials said, especially because of the small circle of distribution.

Trump has told confidants that be believes the leak was meant to embarrass and undermine him, said White House officials and outside advisers familiar with the president's thinking but not authorized to publicly discuss private conversations.

The president has suggested it was done by "the deep state," they said. That's the catchall phrase for career officials and the Washington establishment who, Trump believes, have tried to protect their own grasp on power by sabotaging him.

Trump has insisted that maintaining a strong personal relationship with Putin is the United States' best chance of improving ties with Russia and has signalled to allies that he trusts his own instincts in dealing with the Russian president.

Other leaks of classified material -- including partial transcripts of Trump's calls with foreign leaders -- have not garnered specific warnings of termination or criminal action. It was not clear whether this week's document was classified, but it was included with other classified papers.

It also was unclear whether Trump, who prefers oral briefings, had read the talking points prepared by his national security team before Tuesday's call. McMaster briefed the president in person before the conversation in the White House residence.

The leak further cast doubt on McMaster's longevity in the top foreign policy post. Trump has been moving toward replacing McMaster on the advice of Kelly and Secretary of Defence James Mattis, but has not settled on timing or a successor.

Trump's call of congratulations to Putin drew bruising criticism from members of his own party even before the revelation that he was advised against it.

"An American president does not lead the free world by congratulating dictators on winning sham elections," said Sen. John McCain, R-Ariz., who chairs the Senate Armed Services Committee and has pressed the Trump administration to respond aggressively to Russia's interference in the U.S. presidential election.

Sen. Charles Grassley, R-Iowa, told CNN, "I wouldn't have a conversation with a criminal."

The call was the latest indicator of Trump's personal reluctance to publicly criticize Putin. The White House said Trump did not raise Russia's meddling in the U.S. elections or its suspected involvement in the recent poisoning of a former spy in Britain in the call with Putin. Trump did discuss the attack against Sergei Skripal Wednesday in a call with French President Emmanuel Macron.

Trump also said he and Putin might meet "in the not too distant future" to discuss the arms race and other matters.

He said that during their hoped-for meeting the two men would likely discuss Ukraine, Syria and North Korea.

White House press secretary Sarah Huckabee Sanders defended Trump's call, noting Obama's similar call and saying, "We don't get to dictate how other countries operate."

Florida Sen. Marco Rubio called the leak a "bigger outrage" than Trump's congratulations for Putin. He said on Twitter that "this ongoing pattern of duplicity holds potential for serious damage to the nation."

Russia has received global condemnation after Britain blamed Moscow for the recent nerve agent attack that sickened Sergei Skripal and his daughter. Russia has denied the accusation.

Trump's call came at a period of heightened tension after the White House imposed sanctions on Russia for its interference in the 2016 U.S. election and other "malicious cyberattacks." Sanders insisted that the administration has scolded Putin at the appropriate times.

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Vladimir Isachenkov in Moscow contributed to this story.