US presidential candidate Donald Trump called the winner of his first Miss Universe pageant a pig and bullied her for gaining weight, Hillary Clinton said during the first US presidential debate.

The former secretary of state used the fiery showdown to focus once again on Mr Trump's appalling record of speaking about women.

Close to the end of the 95-minute televised sparring session, Mrs Clinton reminded the audience the Republican candidate is "a man who has called women pigs, slobs and dogs".

She then invoked Alicia Machado.