US congressman David Scott, a Democrat who represented Georgia's 13th District for more than two decades, has died aged 80.

The veteran lawmaker's death was confirmed a day after he cast his final vote in the US House of Representatives.

He was running for a 13th term in next month's primary election, having refused to bow out amid questions over his declining health. Scott became the first black chairman of the House's agriculture committee in 2020.

He is the fifth member of Congress to die in office since last year. His vacant seat hands Republicans in the lower chamber of Congress a narrow advantage as they campaign to defend a razor-thin majority ahead of November's midterm elections.

No cause of death has yet been disclosed for the Georgia lawmaker.