(CNN) Democratic Rep. Ilhan Omar says in the days since President Donald Trump tweeted about a speech she gave last month, she has experienced an increase in death threats.

The Minnesota congresswoman also alleged that Trump is encouraging right-wing extremist violence, a charge White House press secretary Sarah Sanders denied earlier Sunday.

"Since the President's tweet Friday evening, I have experienced an increase in direct threats on my life — many directly referencing or replying to the President's video. I thank the Capitol Police, the FBI, the House Sergeant at Arms, and the Speaker of the House for their attention to these threats," Omar said in a statement released Sunday evening.

House Speaker Nancy Pelosi said Sunday she had spoken with the House Sergeant at Arms about Omar's safety and that she wanted to make sure a security assessment was being conducted.

In his Friday tweet, Trump wrote, "We will never forget!" and included video of a speech Omar gave last month in which she said, "For far too long we have lived with the discomfort of being a second-class citizen and, frankly, I'm tired of it, and every single Muslim in this country should be tired of it. CAIR was founded after 9/11 because they recognized that some people did something and that all of us were starting to lose access to civil liberties."

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