Clinton's health re-emerges as an issue

Hillary Clinton's stumbles as she left Sunday's 9/11 memorial ceremony in New York have put her health at the forefront of the US presidential campaign.

The two major party nominees are among the oldest ever and have disclosed little information about their medical histories.

Clinton "became overheated and dehydrated" at the ground zero event, her doctor said. She left after about 90 minutes, and a video of her departure shows her appearing to stumble as staff members hold her up and help her into a van.