Officials in Minsk told Kavalenka’s relatives and colleagues on March 26 that he was moved overnight to a prison clinic in the eastern city of Vitsebsk.
Kavalenka, 37, was sentenced in Vitsebsk in February to 25 months in jail for an alleged parole violation.
He was later transferred to a prison hospital in Minsk due to poor health.
Kavalenka was detained in December for allegedly violating the terms of his parole for an earlier conviction on charges of "illegally displaying the banned Belarusian national flag."
He began his hunger strike shortly after his detention. Officials force-fed him in January, but he resumed the protest in February.