Story highlights Former acting Attorney General Sally Yates gives in her first interview since her firing

Yates said there was "certainly a criminal statute that was implicated by (Flynn's) conduct."

(CNN) Former acting Attorney General Sally Yates on Tuesday shot down the White House's efforts to downplay the severity of her warnings about former national security adviser Michael Flynn.

"There was nothing casual about this," Yates said in an interview with CNN's Anderson Cooper, reacting to White House press secretary Sean Spicer's assertion that her warning about Flynn's interactions with Russian representatives was a "heads up."

"I absolutely did not use the term heads up," Yates told Cooper. "I called (White House counsel) Don McGahn and told him I had a very sensitive matter I need to discuss with him that day in person."

The exclusive interview, which aired in its entirety Tuesday evening, was Yates' first on television since being fired by President Donald Trump. It was taped on Monday morning, prior to an explosive report by The New York Times that Trump had asked ousted FBI Director James Comey to end the investigation into Flynn.

Earlier this month, Yates testified in front of the Senate Judiciary Committee's Subcommittee on Crime and Terrorism regarding the Trump campaign's alleged ties to Russia, particularly Flynn's contact with Russian Ambassador to the US Sergey Kislyak.