Tsikhanouskaya offered her condolences to Bandarenka's family.
"He became a victim of the regime's inhumanity and terror for just being an active Belarusian thriving for freedom," she wrote on Twitter Nov. 12.
The crisis following the disputed election has engulfed the Catholic Church in Belarus -- the second largest religious body in the country after the Orthodox Church -- and also drawn in the Vatican.
Archbishop Tadeusz Kondrusiewicz, president of the country's Catholic bishops' conference, was prevented from returning to the country on Aug. 31.
The archbishop of Minsk-Mohilev had spoken out in defense of protesters and said he feared the country was heading towards civil war. He prayed outside a prison where detained protesters were reported to have been tortured and also demanded an investigation into reports that riot police blocked the entrance to a Catholic church in Minsk.
Archbishop Paul Gallagher, the Vatican's Secretary for Relations with States, visited Belarus in September in an attempt to resolve the impasse. But Kondrusiewicz remains barred from his homeland.
Earlier this month, Lukashenko, who has served as president of Belarus since the role was created in 1994, received the Holy See's new ambassador to the country, Archbishop Ante Jozić.
The state-owned new agency BelTA reported that Lukashenko told the nuncio that Belarus and the Vatican enjoyed "special relations."
"On the international arena, together we consistently promote such important initiatives as combating human trafficking, combating violence against children, and protecting traditional family values," he said.
He added: "We count on the consolidating and constructive role of the Catholic Church in Belarusian society."