US civil rights campaigner Jesse Jackson his suffering from Parkinson's disease.

In a letter to supporters the 76-year-old said family and friends noticed a change in him about three years ago.

He said he could no longer ignore symptoms of the chronic neurological disorder that causes movement difficulties and had been receiving outpatient care for two years

"Recognition of the effects of this disease on me has been painful, and I have been slow to grasp the gravity of it," he wrote.

"For me, a Parkinson's diagnosis is not a stop sign but rather a signal that I must make lifestyle changes and dedicate myself to physical therapy in hopes of slowing the disease's progression."

He noted that the same disease "bested my father". Noah Lewis Robinson died in 1997 at the age of 88. Jackson runs the Chicago-based Rainbow/PUSH Coalition and was twice a candidate for the Democratic presidential nomination in the 1980s.