In a declaration distributed today by his supporters, Kazulin also says Lukashenka should be tried by an international tribunal.
Kazulin was convicted on charges of organizing an unsanctioned rally against the disputed re-election of Lukashenka in March. He was sentenced to five and a half year in prison. His appeal against the sentence was rejected on September 19.
Kazulin was transferred early on September from a detention facility in Minsk to a jail in Vitebsk, near the frontier with Russia.
Kazulin says he will go on hunger strike indefinitely on October 20 in protest against the current regime.