President Donald Trump, in a series of tweets Tuesday, demanded that Sen. Elizabeth Warren apologize for claiming she had Native American heritage and called the results of her DNA test "bogus" and "useless."

President Trump has repeatedly referred to the possible 2020 presidential contender sarcastically as "Pocahontas" including during an Oval Office event last year honoring Native American code talkers for their service during World War II.

On Tuesday, he renewed the criticism.

"Now that her claims of being of Indian heritage have turned out to be a scam and a lie, Elizabeth Warren should apologize for perpetrating this fraud against the American Public. Harvard called her "a person of color" (amazing con), and would not have taken her otherwise!" Trump said in a tweet.

"Pocahontas (the bad version), sometimes referred to as Elizabeth Warren, is getting slammed. She took a bogus DNA test and it showed that she may be 1/1024, far less than the average American. Now Cherokee Nation denies her, 'DNA test is useless.' Even they don’t want her. Phony!" the president continued.

Warren on Tuesday called Trump's taunts "racist".

Cherokee Nation Secretary of State Chuck Hoskin Jr. responded to Warren's DNA results in a tweet, saying she was "undermining tribal interests" with her claims of heritage.

Hoskin also criticized the president's use of the name "Pocahontas" as an intended insult. Pocahontas, a historical figure often revered for her role as a Colonial-era emissary.

"She doesn't deserve it. And I think it's a term that he means in a derisive way," Hoskin said on CNN on Monday night. "Indian country needs leaders in Washington who understand our issues, not who get in a back and forth of name calling. I don't think the president's particularly helpful in taking those shots at Elizabeth Warren. I don't think she's particularly helpful for going back and saying, look, very my DNA results, see what they show."

Shortly after Warren released her DNA test results, she took to Twitter to ask Trump about the $1 million he promised to donate to charity if she proved her Native American ancestry.

"By the way, @realDonaldTrump: Remember saying on 7/5 that you’d give $1M to a charity of my choice if my DNA showed Native American ancestry? I remember – and here's the verdict. Please send the check to the National Indigenous Women’s Resource Center," Warren tweeted.

On Monday, Trump denied making that claim and said he would only give her the money he promised on the campaign trail if he could administer the DNA test himself.

"That will not be something I enjoy doing either," Trump said.

Warren's DNA results revealed the vast majority of her ancestry is European. But it strongly supported the existence of an unadmixed Native American ancestor in her pedigree from six to 10 generations ago.

The Massachusetts senator first provided the test results to The Boston Globe on Sunday. The test was conducted by Carlos D. Bustamante, a Stanford University professor and an expert in DNA analysis.