No charges are expected by the FBI against former national security adviser, Michael Flynn, regarding a phone call with Moscow's U.S. ambassador, in which he had allegedly discussed sanctions against Russia, CNN reported citing law enforcement officials Thursday.

In an interview with the FBI last month, Flynn had denied speaking to the Russian ambassador, Sergey Kislyak, about U.S. sanctions against Russia. However, his answers were reportedly contradictory to previous data collected by intelligence agencies.

When FBI interviewers asked Flynn about his phone call, he had initially told them that sanctions were not discussed. However, FBI agents probed him further by asking if he was certain about his answer. He then responded that he did not remember.

Lying to the FBI is a felony offense. If Flynn's statements during his interview turn against him, he might be involved in a legal jeopardy. FBI officials reportedly believe Flynn did not mislead them intentionally, but officials also said it was not clear if prosecutors would bring a case against him, the Washington Post reported. The Justice Department would have the authority to ultimately decide if there is a chance of prosecution.

A representative of Flynn reportedly denied response and the Justice Department and the FBI have not commented on the issue yet.

Flynn had formally resigned from his post Monday. Commenting on his resignation, Sean Spicer, the White House press secretary, said during a press briefing: "The evolving and eroding level of trust as a result of this situation and a series of other questionable instances is what led the president to ask General Flynn for his resignation."

Trump called Flynn a "fine person" at a news conference Thursday. Commenting on the resignation of his former national security adviser, Trump said: "He didn't have to do that, because what he did wasn't wrong -- what he did in terms of the information he saw. What was wrong was the way that other people, including yourselves in this room, were given that information, because that was classified information that was given illegally. That's the real problem."

An FBI review on Flynn and Russia-related associations is ongoing.