White House was warned Flynn at risk of blackmail

In the almost three weeks that passed between finding out Flynn misled the Vice President Mike Pence about his contacts with Russia's ambassador to the US and Flynn's resignation, Spicer said, there were no known restrictions to his access to information.

Mr Pence said in January that Mr Flynn denied those calls involved sanctions placed on Russian Federation by the Obama administration in response to its election meddling.

Yates said McGahn asked her, "Why does it matter to the DOJ if one White House official lies to another official?"

Both Clapper and Yates were asked if they had been the source of or had authorized any leaks to the media of classified information.

Spicer said that he was "not aware of any" restrictions placed on Flynn's duties on the National Security Council between the period that Yates warned the White House and that Flynn was ultimately dismissed.

Notably, Trump's own White House requested the House and Senate investigations after he took to Twitter on a Saturday morning and accused Obama of tapping the phones in Trump Tower.

Commenting on this conversation on Fox news, President Donald Trump blamed the Obama administration for not vetting Flynn.

Flynn had been pushed out by Obama in 2014 from his job as director of the Defense Intelligence Agency, or DIA.

The FBI as well as the US Senate and House intelligence committees have been investigating Russia's alleged meddling in the 2016 US presidential election and any possible ties between Trump's associates and Moscow.

That's according to three former Obama administration officials.

The president sought to get out ahead of the any unpleasant disclosures on Monday morning, casting aspersions on Yates - the the 27-year Justice Department prosecutor who warned the White House that Flynn had misled officials about his conversations with the Russian ambassador.

"If President Obama was truly concerned about General Flynn why didn't he suspend his security clearance which they had just reapproved months earlier", asked White House Press Secretary Sean Spicer. "Imagine what Republicans would say if a President Hillary Clinton retained as national security adviser a person who could be blackmailed by Moscow".

"All arguments have to be based on truth", Yates said during testimony before a Senate panel.

Yates, a longtime federal prosecutor and Obama administration holdover, was sacked January 30 by Trump after refusing to defend the administration's travel ban.

Instead, Trump chose to play up former director of national intelligence James Clapper's acknowledgement during the same hearing that he was not aware of any evidence of collusion between the president and Russian Federation, which American intelligence has concluded tried to sway the United States election in Trump's favor.

Mr Trump has dismissed FBI and congressional investigations into his campaign and Russian Federation as a "hoax".