Breaking News: Donald Trump mocks at 'disastrous' Obama

Donald Trump has dismissed Barack Obama's time in the White House as a "disaster" after the US president said he was not fit to succeed him.

"He's been weak, he's been ineffective," Republican candidate Mr Trump said of Mr Obama in a Fox News interview on Tuesday.

Read This: News Update: Donald Trump is unfit to be president - Obama

He mocked Mr Obama's handling of the crisis with Russia over Ukraine.

Earlier, Mr Obama said Mr Trump was unfit to be president, and questioned why his party still backed him.

"There has to come a point at which you say: 'Enough'," Mr Obama said.

Read This: Michelle Obama blasts Donald Trump

French President Francois Hollande joined the chorus of criticism on Tuesday, saying that Mr Trump made people "feel nauseous".

He warned that a Trump presidential election victory could herald a very strong turn to the right around the world

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