The Minnesota Democrat Ilhan Omar called the Colorado Republican Lauren Boebert a buffoon, a bigot and a liar for claiming to have joked about terrorism when sharing an elevator in Congress.

“Fact,” Omar wrote on Twitter on Thursday. “This buffoon looks down when she sees me at the Capitol, this whole story is made up. Sad she thinks bigotry gets her clout.

“Anti-Muslim bigotry isn’t funny and shouldn’t be normalised. Congress can’t be a place where hateful and dangerous Muslims tropes get no condemnation.”

One of the first Muslim women elected to Congress, Omar is also a member of a prominent “Squad” of House progressives.

Boebert is a first-term far-right Trump ally who consistently seeks controversy. Her connections to the deadly attack on the Capitol on 6 January remain under investigation.

She made the comments about Omar in her home district over the Thanksgiving break.

“Actually I have an Ilhan story for you,” Boebert told an audience, to laughter. “So, the other night on the House floor was not my first ‘Jihad Squad’ moment.

“So I was getting into an elevator with one of my staffers. You know, we’re leaving the Capitol and we’re going back to my office and we get an elevator and I see a Capitol police officer running to the elevator. I see fret all over his face, and he’s reaching, and the door’s shutting, like I can’t open it, like what’s happening. I look to my left, and there she is. Ilhan Omar.

“And I said, ‘Well, she doesn’t have a backpack, we should be fine.’

The audience laughed and applauded.

“We only had one floor to go,” Boebert continued. “I said, ‘Oh look, the Jihad Squad decided show up for work today.’”

The audience whooped and applauded again.

“Don’t worry,” said Boebert, “it’s just her staffers on Twitter that talk for her, she’s not tough in person. So … there’s a little bit of interactions with these folks.”

The remarks raised calls for Boebert to face formal censure – as recently did Paul Gosar of Arizona, for tweeting a video which depicted him killing Alexandria Ocasio-Cortez of New York, another prominent progressive, and threatening Joe Biden.

Boebert’s reference to “the other night on the House floor” was to remarks in support of Gosar in which she called Omar “the Jihad Squad member from Minnesota” and repeated rightwing conspiracy theories about her.

In response to those remarks, Omar called Boebert an “insurrectionist who sleeps with a pervert”, a reference to Boebert’s husband, who in 2004 pleaded guilty to public indecency and lewd exposure and spent time in jail. Omar also said Boebert “shamefully defecates and defiles the House”.

In a statement on Friday, Edward Ahmed Mitchell, national deputy director of the Council for American-Islamic Relations (Cair), called Boebert’s remarks “digusting” and “merely the latest symptom of the anti-Muslim bigotry that has plagued the Republican caucus in the House for years”.

“Leader [Kevin] McCarthy should repudiate Representative Boebert’s remarks,” Mitchell said, “and call on all Republican members of Congress to treat their American Muslim colleagues and constituents with the respect and decency everyone deserves.”

Boebert later tweeted an apology “to anyone in the Muslim community I offended with my comment about Representative Omar”.

She also said she had “reached out to her office to speak with her directly. There are plenty of policy differences to focus on without this unnecessary distraction.”

Omar retweeted support from another member of the “Squad”, Cori Bush of Missouri.

“Capitol Hill is a toxic work environment for Muslim members and staff,” Bush wrote, “when bigots routinely spew racist, Islamophobic vitriol unchecked and with no consequence.

“Congresswoman Omar, we love you, and we pray for your well-being and protection from this despicable abuse.”