Former US President Bill Clinton was hospitalized late Thursday with a non-COVID-related illness, according to his spokesperson.

On Tuesday, the 75-year-old was admitted to the University of California Irvine Medical Center.

"He is on the mend, in good spirits, and is incredibly thankful to the doctors, nurses, and staff providing him with excellent care," spokesman Angel Urena said on Twitter.   

CNN reported that Clinton was being treated for a possible blood illness.

Clinton was "admitted to the hospital for close monitoring and administered IV antibiotics and fluids," his physicians, Dr. Alpesh Amin and Dr. Lisa Bardack said in a statement.

"He remains at the hospital for continuous monitoring," the doctors' statement added. "After two days of treatment, his white blood cell count is trending down and he is responding to antibiotics well."

"We hope to have him go home soon," they added. His condition is not related to his previous heart problems or COVID-19, CNN said.

Clinton was the 44th President of the United States, serving from 1993 to 2001.