U.S. President Donald Trump waits for the arrival of Egypt's President Abdel Fattah al-Sisi at the White House in Washington Thomson Reuters Obama administration officials did not act inappropriately in trying to unmask officials on President Donald Trump's transition team whose conversations with foreign officials were incidentally collected during routine intelligence-gathering operations, Republican and Democratic congressional aides told CNN and NBC in recent days.

In an interview with the New York Times earlier this month, Trump claimed that former national security adviser Susan Rice may have committed a "crime" by asking the National Security Agency (NSA) to "unmask" the identities of US persons whose conversations with monitored foreign agents had surfaced in intelligence reports.

Those reports "were summaries of monitored conversations — primarily between foreign officials discussing the Trump transition, but also in some cases direct contact between members of the Trump team and monitored foreign officials," Bloomberg's Eli Lake reported earlier this month.

Trump's accusation, for which he offered no evidence, came after Rep. Devin Nunes — the chairman of the House Intelligence Committee who stepped aside from the committee's Trump-Russia probe earlier this month — bypassed his committee to brief Trump on classified executive-branch reports he said showed that members of the transition team had been swept up in government surveillance.

Trump, who tweeted in early March that President Barack Obama had illegally wiretapped Trump Tower phones, said afterward that he felt "somewhat vindicated" by Nunes' findings. But Nunes reiterated in multiple press conferences that there was still no evidence to suggest that Trump or his team had ever been surveilled illegally.

Nunes' office said in a later statement that the California congressman had been investigating "the possible improper unmasking of names of US citizens," but that investigation was ultimately fruitless.

A senior Republican aide and another US official briefed on the documents told NBC on Monday that they had found no evidence of any wrongdoing.

"It was all completely normal," the US official said.

House Intelligence Committee Chairman Rep. Devin Nunes, R-Calif., right, and the committee's ranking member Rep. Adam Schiff, D-Calif., leave after talking to reporters following a briefing with FBI Director Jim Comey about Russian influence on the American presidential election, Thursday, March 2, 2017, on Capitol Hill in Washington J. Scott Applewhite/AP

A source of concern has been why some of Trump's associates who had been caught up in the surveillance and later unmasked, such as former National Security Adviser Michael Flynn, had their names leaked to the press.

But Rice did not unmask Flynn's name, the Wall Street Journal reported recently, leaving open the question of how The Washington Post learned of Flynn's numerous conversations with Russia's ambassador to the US, Sergei Kislyak, after the election.

National-security experts and former intelligence officials from both Republican and Democratic administrations told Business Insider earlier this month that Rice's requests to unmask US persons were neither unusual nor against the law.

"The identities of US persons may be released under two circumstances: 1) the identity is needed to make sense of the intercept; 2) if a crime is involved in the conversation," said Robert Deitz, a former senior counselor to the CIA director and former general counsel at the National Security Agency.

"Any senior official who receives the underlying intelligence may request these identities," Deitz said, noting that while "the bar for obtaining the identity is not particularly high, it must come from a senior official, and the reason cannot simply be raw curiosity."

Paul Pillar, a 28-year veteran of the CIA and former executive assistant to the CIA's deputy director for intelligence, said Rice's unmasking requests could likely be viewed as routine and expected of high-level intelligence officials.

"There is an unavoidable tension between, on one hand, restricting information to protect the privacy of US persons and, on the other hand, sharing enough information with the consumers of intelligence so that the intelligence report in question is comprehensible and useful," Pillar said in an email.

"This whole story strikes me as just more of the effort to divert attention from the issue of the relations that Trump and his associates have had with Russia," Pillar said, "and as part of the diversion to try to suggest impropriety of some sort on the part of the Obama administration."