Politician Vintsuk Vyachorka told RFE/RL that Belarusian border guards, early on March 22, asked him to get off a train heading to Prague.
According to Vyachorka, who was traveling with his daughter on what he described as a private trip, the guards did not provide an explanation for removing him from the train.
In recent weeks, at least 12 Belarusian activists, politicians, and journalists have been prevented from traveling west to European Union countries.
President Alyaksandr Lukashenka confirmed on March 21 that his government has compiled a list of political opponents who are barred from leaving Belarus.
He accused opposition activists of running a "fifth column," or of being disloyal, by supporting additional EU sanctions against his regime.