Donald Trump is ramping up his attacks on the judge overseeing Trump University fraud cases

Donald Trump ramped up his racially tinged attacks on the judge presiding over the fraud lawsuits against Trump University.

In an interview with The Wall Street Journal, Trump said US District Judge Gonzalo Curiel had" an absolute conflict" in presiding over the civil cases against Trump University because Curiel was "of Mexican heritage," as Trump put it, and belonged to a Latino lawyers association.

The presumptive Republican presidential nominee said Curiel's ethnic background was relevant because of his campaign promises to build a wall on the Mexican border and deport immigrants who are in the country illegally.

"I'm building a wall. It's an inherent conflict of interest," Trump said, according to The Journal.

Trump's rhetoric against Curiel has alarmed a number of legal experts who view his comments as an attack on judicial independence.

"If this continues, I would hope that some prominent federal judges would set Mr. Trump straight on what's appropriate and what's not in our democracy," University of Pennsylvania law professor Stephen Burbank told The Journal.

Trump's comments on Thursday follow a long line of attacks against specific ethnic groups that have underscored his campaign's platform.