The war between Republican presidential candidate Donald Trump and Fox News anchor Megyn Kelly continued this week after Trump called her "biased" and threatened to boycott the upcoming GOP debate that she will be moderating.

In an interview on CNN's "Situation Room," Trump said he's not "100 percent" sure that he will participate in Thursday's GOP debate hosted by the Fox News Channel and Google because he doesn't think Kelly is capable of treating him fairly.

"Nothing's 100 percent, I'm not 100 percent," Trump told Wolf Blizter on Monday. "I'll see. If I think I'm going to be treated unfairly, I'd do something else. I don't think she can treat me fairly, I think she's very biased. But that doesn't mean I don't do the debate. I like doing debates."

The feud began at the first Republican debate last August when Kelly called him out over his history of sexism, asking him if previous remarks he had made were a "part of the war on women."

Following the debate, the real estate mogul accused the network and Kelly of asking him tougher questions than the other candidates. Trump also suggested that Kelly was negatively affected by her menstruation during the debate.

In response, Kelly said that probing questions is part of her job.

On Monday, Trump didn't hold back his contempt towards the host of "The Kelly File."

"I don't like her," he said bluntly. "She doesn't treat me fairly. I'm not a big fan of hers at all."

"But that doesn't mean I don't do the debate," he continued. "I like doing the debates. I've won every single debate according to every single poll ... so I want to do the debates, they're good for me. But I don't think she can treat me fairly and I'm not a big fan of hers. Maybe I know too much about her."

Fox News responded by releasing a statement defending Kelly and their decision to allow her to host their next debate.

"Sooner or later Donald Trump, even if he's president, is going to have to learn that he doesn't get to pick the journalists - we're very surprised he's willing to show that much fear about being questioned by Megyn Kelly," reads the statement, according to The Hill.

Still, the GOP front-runner continued to blast Kelly during an interview on Good Morning America Tuesday, calling her unprofessional, untalented and incompetent, reports 9 News.

Watch a clip of Donald Trump's CNN interview.