US Democratic Presidential candidate Hillary Clinton has released further information relating to her medical records.

In a letter posted on the Clinton campaign website, Mrs Clinton's doctor said that she was healthy and had suffered an ear and sinus infection earlier in the year, in addition to her current bout of pneumonia.

The health of the candidates has become an issue in the campaign as the Republican Party has raised questions over Mrs Clinton's health, which increased following her diagnosis with pneumonia which forced her to leave a 9/11 memorial on Sunday early.

Dr Lisa Bardack released an updated health summary on Mrs Clinton, following on from her initial letter published in July 2015.

In today's letter, Mrs Clinton's doctor says her "overall impression" is that Mrs Clinton has "remained healthy" throughout the year.

She said that is "healthy and fit to serve as President of the United States".

Dr Bardack released Mrs Clinton's laboratory results that showed "normal" readings for cholesterol, triglycerides and other key readings.

Her campaign had been pressed to be more transparent about Mrs Clinton's health, particularly after it failed to reveal her Friday pneumonia diagnosis until Sunday, when she nearly collapsed as she left the Ground Zero site in New York.

Her rival Donald Trump is also being called on to reveal his own medical records, something he has not done save for a brief letter released last year by Harold Bornstein, the Republican nominee's doctor for 35 years.

Dr Bornstein then wrote that Mr Trump's health was "excellent" and that a recent examination "showed only positive results."

Mr Trump had another physical in recent days, and he went on the television set of celebrity doctor Mehmet Oz today to disclose his new health records. 

In a statement, the show said: "Dr Oz took Mr Trump through a full review of systems."