US Democratic presidential candidate Hillary Clinton felt unwell at a 9/11 ceremony in New York but is now better, her campaign says.

She had "felt overheated so departed to go to her daughter's apartment", the campaign said.

Clinton's Republican opponent, Donald Trump, has previously raised concerns about her health.

Her doctors say she made a full recovery from surgery she underwent in 2012 for a blood clot.

Clinton's personal doctor Lisa Bardack said last month she was "in excellent health and fit to serve as president of the United States".

The Clinton campaign has accused the Trump campaign of pushing a "deranged conspiracy about Clinton's health".

Clinton is 68 and Trump is 70.

An unnamed law enforcement source told US broadcaster Fox News Clinton had suffered a "medical episode" which required her to leave the New York ceremony early. She then appeared to faint on her way to her van, Fox said.

An unnamed witness also quoted by Fox said Mrs Clinton had stumbled off the kerb. Her "knees buckled" and she lost a shoe as she was helped into the van, the witness added.

Fox's account of the events could not be independently verified.

(BBC)