Fox News issued an apology after a panelist described Swedish climate activist Greta Thunberg as “a mentally ill Swedish child.”

The Monday night “The Story with Martha MacCallum” panel featured conservative podcaster Michael Knowles matched up against Democratic Party activist and frequent Fox News guest Chris Hahn. Hahn took immediate and dramatic umbrage at Knowles’ characterization of Thunberg during his commentary about environmentalists’ opposition to eating meat.

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“[Meatless diets] increase emissions, the increased energy use, water use, but none of that matters because the climate hysteria movement is not about science,” said Knowles. “If it were about science, it would be led by scientists rather than by politicians and a mentally ill Swedish child who is being exploited by her parents and by the international left. So what you’re seeing is a political movement and a religious movement, and it’s fulfilling religious and political goals of the left, but it isn’t doing that much for science.”

Hahn could be heard scoffing and saying “how dare you” in the background, reacting to Knowles’ comment.

“You’re a grown man and you’re attacking a child,” he said later. “Shame on you.”

“I’m not, I’m attacking the left for exploiting a mentally ill child,” Knowles responded.

“Relax, skinny boy!” said Hahn. “I got this, okay? You’re attacking a child. You’re a grown man. Have some couth, ok, when you’re on television.”

Knowles insisted that he was simply “attacking the left for exploiting a mentally ill child.”

“Maybe on your podcast you can get away and say whatever you want because nobody is listening,” said Hahn. “You’re on national television. Be a grown-up when you’re talking about children. She’s trying to save the planet because your president doesn’t believe in climate change. And kids need to take to the streets to worry about their future. You are despicable for talking about her like that and you should apologize on national television right now.”

Knowles noted that Thunberg is, in fact, “mentally ill” through Hahn’s insistence on taking the comment back. (RELATED: Tucker: Greta Thunberg Is ‘A Kind Of Human Shield’ Politicians Use To ‘Demand Power’)

“She has autism,” he said. “She has obsessive-compulsive disorder. She has selective mutism. She had depression.”

Fox News guest-host Harris Faulkner moved the panelists to another topic. Later, the network provided a statement of apology:

The comment made by Michael Knowles who was a guest on The Story tonight was disgraceful. We apologize to Greta Thunberg and to our viewers.

Knowles later defended himself on Twitter, retweeting several tweets of support and commenting back at some of his critics:

There is nothing shameful about living with mental disorders. Your suggestion to the contrary is not only wrong but deeply offensive. Did Greta’s mother insult her when she wrote a book describing the child’s struggles with mental and developmental disorders? https://t.co/IhMd0e6K2B — Michael Knowles (@michaeljknowles) September 24, 2019