US President Joe Biden on Saturday tested negative for Covid-19, days after coming down with a second bout of the illness.

"The President continues to feel very well," Biden's physician Kevin O'Connor said in a statement. "This morning, his SARS-CoV-2 antigen testing was negative."

Biden, who at 79 is the oldest person to hold the US presidency, has been in quarantine for the past week, after testing positive for the virus following an initial recovery in what is known as a "rebound" case.

O'Connor said Biden will continue to isolate pending a second negative test "in an abundance of caution."

According to Biden's official schedule he is set to travel to the southern state of Kentucky, the scene of devastating floods, on Monday.