Former US President Jimmy Carter says recent liver surgery revealed that he has cancer and it has spread to other parts of his body.
The 90-year-old statesman underwent surgery to remove a small mass in his liver earlier this month.
He said he would reveal more "when facts are known, possibly next week".
Mr Carter will undergo treatment by physicians at Emory Healthcare in Atlanta.
President Barack Obama wished Mr Carter "a full and fast recovery" in a statement released on Wednesday.
"Jimmy, you're as resilient as they come, and along with the rest of America, we are rooting for you," Mr Obama said.
The White House said Mr Obama spoke to Mr Carter on the telephone on Wednesday.
Bernice King, daughter of Martin Luther King Jr, posted on Twitter: "President #JimmyCarter is in my thoughts & prayers. May the Lord heal, comfort & encourage this extraordinary servant-leader to the world." READ MORE OF THIS STORY