Former National Security Advisor Susan Rice has been accused of ordering the unmasking of Donald Trump associates who were under "incidental surveillance."

Responding to the accusation, Rice suggested in an MSNBC interview on Tuesday that she "absolutely" did not order the unmasking of individuals for political purposes. She also suggested that sometimes such a request would be necessary for an investigation.

Rice now faces growing calls from lawmakers to testify under oath.

Ari Fleischer, former press secretary under President George W. Bush, says that Rice needs to testify because there are serious unanswered questions.

"Unmasking is the authority of the national security advisor, but what did you do with that information?" Fleischer said on Fox News Channel this afternoon. "Did you provide it to anybody? Did you provide it to your staff? Did you provide it to any communications people at the White House? Could they may have given it to the media? Can you assure us nobody you gave it to leaked it?"

Fleischer said he also wants to know why Rice last month claimed she knew "nothing" about the intelligence reports.

"When journalists hear somebody change their tune - particularly somebody who now looks like they're on a hot seat - it makes them suspect," Fleischer said.

He said he expects Congress to ask Rice those questions and many more, likely beginning in a classified session.

Watch the full MSNBC interview below, and see Tucker Carlson grill a former Obama aide on surveillance and Russia.

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Graham: Rice Has History of 'Political Manipulation' of Nat'l Security Information

Unmasking Reporter Speaks Out: 'How Long Has This Thing Been Going On?'

Hannity: Susan Rice 'Has a Lot of Explaining to Do' About Intel 'Unmasking'