TV host Mika Brzezinski has responded to disrespectful comments tweeted by Donald Trump.

The co-hosts of MSNBC’s Morning Joe program have struck back against crude tweets sent out by President Donald Trump.

In an op-ed in Friday’s Washington Post—co-signed by anchors Mika Brzezinski and Joe Scarborough and entitled “Donald Trump is not well”—the cable television talk show hosts acknowledged making critical statements about Trump’s presidency but said that “our concerns about his unmoored behaviour go far beyond the personal.”

They added, "America's leaders and allies are asking themselves yet again whether this man is fit to be president."

"We have out doubts," they wrote, "but we are both certain that the man is not mentally equipped to continue watching our show."

Trump on Thursday sent a Twitter post calling the pair "low I.Q. Crazy Mika, along with Psycho Joe."

He also wrote that Mika was "bleeding badly from a face-lift" when they met at an event around New Year's Eve.

Mika and Joe claim this is not the case: "Putting aside Mr. Trump's never-ending obsession with women's blood, Mika and her face were perfectly intact, as pictures from that night reveal," they wrote.

I heard poorly rated @Morning_Joe speaks badly of me (don't watch anymore). Then how come low I.Q. Crazy Mika, along with Psycho Joe, came..

— Donald J. Trump (@realDonaldTrump) June 29, 2017

...to Mar-a-Lago 3 nights in a row around New Year's Eve, and insisted on joining me. She was bleeding badly from a face-lift. I said no!

— Donald J. Trump (@realDonaldTrump) June 29, 2017

Speaking on Morning Joe on Friday morning (U.S. time), Mika assured fans she was "fine" following Trump's personal attacks.

"My family brought me up really tough, this is absolutely nothing, for my personally," she said. "But I am very concerned about what this once again reveals about the President of the United States."

She added that the past 24 hours had been "fascinating and frightening and really sad for our country."

Trump's crude comments drew bipartisan howls of outrage and left fellow Republicans beseeching him: Stop, please just stop.

Trump's tweets revived concerns about his views of women in a city where civility already is in short supply and he is struggling for any support he can get for his proposals on health care, immigration and other controversial issues.

The tweets served to unite Democrats and Republicans for once in a chorus of protest that amounted to perhaps the loudest outcry since Trump took office.

"Obviously I don't see that as an appropriate comment," said Republican House Speaker Paul Ryan.

House Democratic leader Nancy Pelosi called Trump's tweets, "blatantly sexist." The president, she added, "happens to disrespect women ... it's sad."

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White House spokeswoman Sarah Huckabee Sanders said the president was "pushing back against people who have attacked him day after day after day. Where is the outrage on that?

"The American people elected a fighter," she added. "They didn't elect somebody to sit back and do nothing."

First Lady Melania Trump, who has vowed to fight cyberbullying while her husband is president, gave his tweets a pass.

"As the first lady has stated publicly in the past, when her husband gets attacked, he will punch back 10 times harder," Stephanie Grisham,her communications director, said in a statement.

About two hours before his tweets, Brzezinski said on the show that "it's not normal behaviour" for any leader to be tweeting about people's appearances or to be bullying, lying, undermining managers and throwing people under the bus.

She said that if any business executive behaved the way Trump does, "there would be concern that perhaps the person who runs the company is out of his mind."

On Wednesday, she had mocked Trump after a story in The Washington Post said he had posted fake Time magazine covers of himself in some of his golf resorts.