Hilary Clinton

Addressing the Congressional Black Caucus gala for the last time as president, Obama warned that while his name would not be on the ballot in November, all of the progress that the country has made over the last eight years was on the line.

Mr Trump suggested Mrs Clinton's security detail should give up their guns and "see what happens to her".

He told supporters his rival wanted to "destroy your second amendment" - referring to the right to own guns.

Mrs Clinton's team has accused Mr Trump of "inciting people to violence".

Speaking at a rally in Miami on Friday, the Republican candidate said: "I think that her bodyguards should drop all weapons. They should disarm, right?'

Mr Trump released the letter following a recent physical examination by Dr Harold N Bornstein.

The 70-year-old is listed as 6 foot 3 inches (1.9 metres) and weighs 236 pounds (107 kilos).

The letter comes as his rival Hillary Clinton returns to the campaign trail after time off with pneumonia, appearing briefly to reporters.

Boarding a plane in White Plains, New York, she spoke to journalists as she heads to North Carolina to hold a rally, her first campaign event since the weekend.

The statement said the Democratic presidential nominee "continues to improve" after a pneumonia diagnosis.

The disclosure came as her Republican rival Donald Trump released health data of his own on a medical chat show.

Clinton aides say she will return to the campaign trail on Thursday after falling ill in public at the weekend.

Both candidates, among the oldest ever to run for the White House, have been under intense pressure to share more medical information.

Mr Trump said health had now become "an issue" in the election campaign.

Mrs Clinton was taken ill on Sunday at a 9/11 memorial ceremony and cancelled a campaign trip to California.

She will also be releasing new medical records to help ease concerns about her health, a campaign spokesman said.

"There's no other undisclosed condition. The pneumonia is the extent of it," Brian Fallon told MSNBC.

He said she would probably resume campaigning in the next few days.

Mrs Clinton said on Twitter she was "anxious" to return to the trail.

Now he's embarking on a visit to North America and making it clear he doesn't care for Donald Trump's talk of a ban on those who share his faith, even though the GOP nominee has softened his stance on the issue, limiting it to Muslims coming from countries with heavy terrorist activity.

"I'm a firm believer in building bridges rather than walls," Khan said in an interview with CNN's Fareed Zakaria that aired Sunday.

Her swoon Sunday at muggy Ground Zero -- and damaging video of Clinton lurching into the arms of her security detail -- dramatically turned the state of her health from conservative conspiracy theory into a genuine campaign issue.

The episode also exacerbates questions about transparency that have long dogged Clinton's White House bid after the campaign revealed the Democratic nominee is suffering from pneumonia -- a fact it kept quiet since Friday.

Dr Lisa Bardack said she was diagnosed with pneumonia on Friday and given antibiotics, but had become dehydrated at the New York event.

Video shows her being supported by aides as they put her into her van after she left the ceremony early.

The doctor's statement said she was now re-hydrated and "recovering nicely".

"Secretary Clinton has been experiencing a cough related to allergies. On Friday, during follow up evaluation of her prolonged cough, she was diagnosed with pneumonia," Dr Bardack's statement said.

But the Democrat launched a furious attack on her Republican opponent and promised to keep fighting "bigotry and racist rhetoric".

Mr Trump had responded by saying the comment was "insulting" to "millions of amazing, hard working people".

Opinion polls suggest Mr Trump is gaining on Mrs Clinton.

The rivals are neck and neck in the key battleground states of Ohio and Florida.

Speaking at a fundraiser, she said they were "racist, sexist, xenophobic, Islamophobic - you name it".

She then went on to say the rest of the Republican nominee's supporters were "just desperate for change".

Mr Trump's campaign manager said Mrs Clinton had insulted "millions of Americans", with her comments.

Polls released earlier this week suggest Mr Trump is gaining on Mrs Clinton, and the rivals are neck-and-neck in the key battleground states of Ohio and Florida.

In other developments: