A judge, called a "hater" by Donald Trump for his handling of a lawsuit related to the businessman's Trump University real estate school, has unsealed documents related to the case.

Trump, the presumptive Republican presidential nominee, is fighting a lawsuit that accuses his school venture of misleading thousands of people who paid up to $35,000 for seminars to learn about the billionaire's real estate investment strategies.

In an order signed on Friday, U.S. District Judge Gonzalo Curiel said that materials, including Trump University procedures on dealing with students and the media, should be unsealed.