Donald Trump will not become US president because the voters realise it is a serious job, Barack Obama said.

Mr Obama contrasted the reality of being president with the rhetoric on the campaign trail, saying doing the job is not like hosting a reality show or a talk show.

The president was speaking after hosting a summit with south-east Asian leaders, and warned that foreign observers are "troubled" by the Republican primaries and debates.

Mr Obama said other countries count on the US to side with science and common sense, and he criticised Republican presidential candidates for harsh talk about Muslims and immigration and for questioning climate change.

He said: "This is not just Mr Trump." Mr Obama predicted that US voters will "make a sensible choice in the end".

Mr Trump hit back, saying the president's prediction that he will not be elected to the White House "actually is a great compliment".

The billionaire developer outlined his complaints about Mr Obama's presidency, saying: "You look at our budgets, you look at our spending, we can't beat ISIS. Obamacare is terrible ... Our borders are like Swiss cheese."

Answering questions at a campaign event at a school in Beaufort, South Carolina, he said Mr Obama "has done such a bad job, he's set us back so far, that for him to say that actually is a great compliment".

Mr Trump added that Mr Obama was "lucky I didn't run last time, when Romney ran, because you would have been a one-term president".