Trump spars with TV reporters Megyn Kelly and Jorge Ramos

Donald Trump has been hitting back at Fox host Megyn Kelly since she hosted the first Republican debate two weeks ago

Republican presidential frontrunner Donald Trump has clashed with two television reporters.

He revived his feud with the Fox News channel host Megyn Kelly - who returned to her show on Monday after a break - saying she must have had a bad holiday because "she's really off her game".

Fox News chief Roger Ailes has demanded an apology, describing the business mogul's verbal attack as "disturbing".

Separately, Mr Trump had a journalist ejected from a news conference.

Univision news anchor Jorge Ramos was trying to question Mr Trump about his call to deport 11 million undocumented immigrants from the US and build a wall the length of the Mexican border.

But Mr Trump insisted that he had not been invited to submit a question.

"You haven't been called, go back to Univision," Mr Trump said, before Mr Ramos was ejected from the news conference.

As security officers approached the Mexican-American journalist, he said: "I am a reporter. Don't touch me. I have a right to ask the question."

In an interview with CNN on Monday, Mr Ramos had accused Mr Trump of disseminating hate by calling for mass deportations of families in the US who do not have the right documentation.

Verbal attack

Mr Trump's clash with Ms Kelly comes two weeks after controversy over his remarks about her following the first Republican debate.

Univision reporter Jorge Ramos was told by Mr Trump that it was not his turn to submit a question

In a CNN interview, Mr Trump said the Fox presenter "had blood coming out of her eyes, blood coming out of her wherever" to describe the way she questioned him during the debate over comments he had made about women.

He was subsequently dropped as a speaker at a major US conservative forum, and his comment was denounced by rival Republican candidates.

But it did not stop Mr Trump from continuing his verbal attack of Ms Kelly during her show on Monday, tweeting: "Kelly File was much better without Megyn Kelly. Her replacement while she was out on vacation was much better!"

He also retweeted a message that referred to her as a "bimbo".

Fox News chairman Roger Ailes, who had cleared the air with Mr Trump after the debate, reacted strongly to the "surprise and unprovoked attack" on his news host. In a statement read aloud on the channel, he said it was "as unacceptable as it is disturbing".

Kelly "represents the very best of American journalism and all of us at Fox News Channel reject the crude and irresponsible attempts to suggest otherwise," he added, demanding an apology.

Some of Ms Kelly's colleagues also came to her defence, including Bret Baier, her co-host for the debate, who tweeted "this needs to stop".

But Donald Trump seemed unfazed by the criticism, saying he disagreed with Mr Ailes' statement and that he did not consider Ms Kelly "a quality journalist".

Likewise he said that he did not believe he had ever met Mr Ramos except when the reporter "started screaming" at the press conference.

The news anchor was later allowed to return to the press conference and submit questions.

Donald Trump has a big opinion poll lead over the 16 other Republican candidates, despite a string of controversial remarks since launching his campaign.

2016 runners and riders

Clockwise from top left: Donald Trump, Jeb Bush, Ben Carson, Marco Rubio, Bernie Sanders, Hillary Clinton

• The early Republican frontrunner is Donald Trump

• Hillary Clinton will have learnt much from her failed campaign of 2008

• Florida senator Marco Rubio lost some right-wing fans by backing a bipartisan immigration reform package

• Retired neurosurgeon Ben Carson is gaining popularity despite making some outlandish comments

• Former Florida governor Jeb Bush is not doing well in the polls despite his name recognition

• Veteran congressman Bernie Sanders is drawing huge crowds at his rallies

Meet all of the 2016 hopefuls