Police in New York say Zambian President Michael Sata was treated by State Department doctors in his hotel this week, but was not hospitalized.
No other details on his condition were available.
Sata was in New York for the annual gathering of world leaders at the United Nations General Assembly, where he was scheduled to speak Wednesday.
He did not deliver the address to the 193-member world body.
The 77-year-old president had not been seen in public in almost three months before he attended the opening of Zambian parliament last week.
At the start of his address in Lusaka, Sata jokingly told the legislative body, "I am not dead."
Concerns about Sata's health have been mounting in Zambia since he traveled to Israel for medical treatment in June and then withdrew from the public eye.