Donald Trump has mocked the physical appearance of fellow Republican US presidential candidate Carly Fiorina, saying: "Look at that face. Would anyone vote for that?"

The comments by the billionaire real estate developer published in an article on the website of Rolling Stone magazine were aimed at the only woman in the large field of Republicans vying for their party's 2016 presidential nomination.

The magazine reported that Mr Trump, leading in the polls among the Republican contenders, made the remarks while watching Ms Fiorina, the former Hewlett-Packard Co chief executive, on television.

"Can you imagine that, the face of our next president?" Mr Trump is quoted as saying.

Ms Fiorina said she viewed Mr Trump's remarks as "very serious."

"Maybe, just maybe, I'm getting under his skin a little bit because I am climbing in the polls," she said.