U.S. Vice President Kamala Harris released a letter from her doctor confirming her good health and suitability for high office while urging her opponent, Donald Trump, to do the same.

"Today I released my medical records, as has, I believe, every candidate for president of the United States except Donald Trump in this election cycle," Harris was quoted as saying by foreign media. She called this "a further example of his lack of transparency."

"I think it's obvious that his team, at least, does not want the American people to see everything about who he is," the vice president added.

According to Harris's physician, Joshua Simmons, her most recent physical exam in April was "unremarkable."

He noted that she maintains an active lifestyle and follows "a very healthy diet" despite her demanding schedule.

Simmons also disclosed that Harris experiences seasonal allergies, manageable with over-the-counter medication.

"She possesses the physical and mental resiliency required to successfully execute the duties of the Presidency, to include those as Chief Executive, Head of State and Commander in Chief," the doctor wrote, as shown in a memo distributed by the White House.

The Harris campaign hopes to emphasize the contrast between her youth and mental sharpness and Trump's age and occasional incoherence to sway undecided voters.

If re-elected, Trump would become the oldest person to serve as US president by the end of his second term, surpassing President Joe Biden, who will turn 82 in November.

Biden was supposed to run for re-election but stepped aside as the Democratic standard bearer following a poor debate performance against Trump.

Following Harris' release of her medical records, Trump's camp noted that the former president had previously shared health updates from his physician.