Opposition leader Svetlana Tikhanovskaya has left Belarus and is "safe" in Lithuania, Lithuanian Foreign Minister Linas Linkevicius says.
Ms Tikhanovskaya's departure came as protests went on for a second day over Sunday's disputed presidential poll.
Her campaign team said she was avoiding the protests because of "possible provocations".
Election results gave President Alexander Lukashenko 80%, but Ms Tikhanovskaya refuses to accept them.
A lack of scrutiny, with no observers present, has led to allegations of widespread vote-rigging in the poll. The US and EU have condemned the vote.
Mr Lukashenko, in power since 1994, has described opposition supporters as "sheep" controlled from abroad.
Police in Belarus's capital Minsk fired rubber bullets for a second night to quash protests, and officials say one demonstrator died when an explosive device went off in his hands - the first confirmed fatality since the clashes began.
"She [Tikhanovskaya] arrived in Lithuania and is safe," Foreign Minister Linas Linkevicius was quoted by news agency AFP as saying.