US Vice President Kamala Harris

Ms Harris, 57, was in control for 85 minutes, while Mr Biden was placed under anaesthesia for a routine colonoscopy on Friday.

Mr Biden's doctor released a statement after the operation, saying he was healthy and able to execute his duties.

The medical examination came on the eve of the president's 79th birthday.

Ms Harris carried out her duties from her office in the West Wing of the White House, officials said.

She is the first woman - and the first black and South Asian American - to be elected US vice-president.

A US senator from California the past four years, Harris has shattered many a glass ceiling. She served as San Francisco's first female district attorney and was California's first woman of colour to be elected attorney general.

She was sworn in by US Supreme Court Justice Sonia Sotomayor, the court's first Latina member.

Looking ahead, Harris, 56, is seen as an obvious contender for the Democratic Party's 2024 presidential nomination should Biden, 78, decide not to seek a second term. Harris has yet to weigh in publicly on such speculation.