NEW YORK -- CNN anchor Don Lemon will return to work Wednesday and will receive "formal training" in the aftermath of his on-air comments about Republican presidential candidate Nikki Haley, network CEO Chris Licht said in an email to employees Monday night.

The memo, obtained by The Associated Press, did not specify the training. Licht added that it was important to him that the network "balances accountability with … fostering a culture in which people can own, learn and grow from their mistakes."

Lemon has not been on the air since Thursday, when he said the 51-year-old Haley was not "in her prime" during the broadcast of "CNN This Morning." Lemon and fellow hosts Poppy Harlow and Kaitlan Collins had been discussing Haley's suggestion that politicians over 75 should be subject to mandatory mental competency tests.

"Nikki Haley isn't in her prime, sorry," Lemon said, explaining why he was "uncomfortable" with the age discussion. He said a woman is considered to be in her prime in her 20s, 30s and maybe her 40s. Haley is 51.

He was challenged by Harlow, who tried to clarify what Lemon was referencing: "I think we need to qualify. Are you talking about prime for childbearing or are you talking about prime for being president?"

"Don't shoot the messenger, I'm just saying what the facts are," Lemon responded. He brought up the subject again an hour later, and was rebutted by commentator Audie Cornish.

"She's in her prime for running for office," Cornish said of Haley. "Political prime is what we're talking about."

Lemon issued a statement that same day saying he regretted his "inartful and irrelevant" comments, which were widely condemned. Haley herself called the comments sexist and used the episode to fundraise.

According to The New York Times, Licht chastised Lemon during an editorial call Friday, saying his remarks were "upsetting, unacceptable and unfair" and a "huge distraction." Lemon appeared at the meeting and apologized to staffers, CNN reported.

"I sat down with Don and had a frank and meaningful conversation," Licht wrote in the Monday night memo. "He has agreed to participate in formal training, as well as continuing to listen and learn. We take this situation very seriously."

Harlow said at the top of Tuesday morning's show that Lemon would be back the next day.

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AP Media Writer David Bauder contributed to this report.