Donald Trump has mocked former secretary of state Hillary Clinton for apparently taking a toilet break during a televised Democratic debate.

The Republican presidential hopeful told supporters at a rally in Michigan: “I know where she went. It’s disgusting.”

Hillary Clinton returned to the stage late after an advert break during December 19 debate with her party rivals for the presidential nomination.

Donald Trump also said Hillary Clinton had been “schlonged” by Barack Obama in 2008.

Using a vulgar Yiddish term, the Republican frontrunner was referring to Hillary Clinton’s defeat to the then senator in the primary contests that year.

Photo CBS News

“Even her race to Obama. She was going to beat Obama. I don’t know who’d be worse. I don’t know. How does it get worse?

“She was favored to win and she got schlonged, she lost.”

It is not the first time Donald Trump has referred to women in a controversial way.

In August, the property tycoon implied that he received tough questions from Fox News debate host Megyn Kelly because she was menstruating.

He has previously described comedian Rosie O’Donnell as a “fat pig”.

Hillary Clinton and Donald Trump have been feuding in recent days over claims she made that ISIS was using Donald Trump’s videos as a recruiting tool.

The billionaire has called for Muslims to be banned from entering the United States, in light of the San Bernardino deadly terror attack carried out by a radicalized Muslim couple.

Donald Trump, who has no political experience, leads the polls nationally among Republican voters, and is also ahead in some key states.

The primary contests begin at the start of February and the presidential election is in November 2016.