Clinton diagnosed with pneumonia: Doctor

New York: US Democratic presidential nominee Hillary Clinton was diagnosed with pneumonia at home after she fell sick during a memorial service marking the 15th anniversary of the September 11 terror attacks here on Sunday.

"She was put on antibiotics and advised to rest and modify her schedule. While at this morning's event, she became overheated and dehydrated. I have just examined her and she is now re-hydrated and recovering nicely," Xinhua quoted physician Lisa Bardack as saying.

A video posted on Twitter shows the 68-year-old Clinton stumbled and she was being helped by her staff into a waiting van and left the memorial service early.

According to her campaign, Clinton had a rest in her daughter's apartment in Manhattan. As she went out the apartment shortly before noon, Clinton said, "I'm feeling great."

Clinton's rival, Republican presidential candidate Donald Trump and his supporters have questioned Clinton's health, saying Clinton is physically unfit for the White House, accusing her of being "exhausted" and sleeping too much.