Hillary Clinton has gone on the attack against rival presidential candidate Donald Trump, calling the real estate mogul a "fraud" who would "scam America" if he became president. Speaking at Rutgers University in Newark, New Jersey, the Democratic frontrunner referred to court documents released on the now-defunct Trump University, which revealed ruthless sales practices designed to push students to sign up for expensive courses.

The real estate school is at the centre of multiple class-action lawsuits in California over allegations that it misled students.

"Trump and his colleagues took advantage of vulnerable Americans, encouraging them to max out their credit cards, empty their retirement savings, destroy their financial futures — all while making promises they knew were false from the beginning," Clinton was quoted as saying by the Guardian newspaper.

"This is just more evidence that Donald Trump himself is a fraud. He is trying to scam America the way he scammed all those people at Trump U."

Dubious business practices

Details about the moneymaking operations of Trump University came to light on 1 June, after a federal judge in California ordered internal court documents to be released. They included "playbooks" that advised employees on ways they could zero-in on desperate students — presumably in a financial sense — and pressure them to pay for courses that cost as much as $35,000 (‎£24,000) a year.

Plaintiffs allege that the school did not deliver on its promise to teach students the secrets of Trump's success in real estate but the billionaire businessman disputes this.

In ordering the court documents to be released, US District Court Judge Gonzalo Curiel argued the information contained in them is in the public interest as Trump had effectively secured the Republican presidential nomination.

"Trump's candidacy is built on his business 'credibility'. But his business record matches his character — his only concern is his own profit," Clinton wrote on Twitter. "The Trump University con says a lot about Trump. If you can't trust him with your personal finances — how can we trust him with our country?"

Clinton is in the midst of a legal wrangle herself concerning her use of a private e-mail system while serving as the US secretary of state.