The Senate Foreign Relations Committee has halted its consideration of former White House aide K.T. McFarland for ambassador to Singapore due to new concerns about her contacts with Russian officials.

"Her nomination is frozen for awhile until that gets worked out. We'll deal with it in appropriate time," Republican Sen. Bob Corker, who chairs the committee, told reporters on Tuesday,

"She has to know that herself," he added.

McFarland was heavily involved in the presidential transition and later became deputy White House national security adviser under Michael Flynn, who pled guilty to perjury charges late last week. Flynn admitted to lying to federal investigators about his correspondence with former Russian ambassador Sergey Kislyak during the transition.

In written testimony in July, McFarland told Sen. Cory Booker, D-N.J., she had never spoken to Flynn about his relationship with Kislyak.

"I am not aware of any of the issues or events described above," she had written.

However, McFarland reportedly indicated in an email exchange last December that she was aware of a phone call between Flynn and Kislyak that took place on Dec. 29, 2016. The emails were first reported by the New York Times earlier this week.

"If she did testify inappropriately, that's a big, big problem," Corker said.

McFarland was formally nominated for the ambassadorship in mid-June. It is unclear exactly when she left the National Security Council to prepare for confirmation hearings.