Belarusian Nobel Prize-winning author and key opposition figure Svetlana Alexievich has left the country for treatment in Germany, her aide says.
She says the trip is not linked to politics and Ms Alexievich will return.
On Sunday, police held scores of people at the latest rally against President Alexander Lukashenko, following last month's disputed election.
Separately, French President Emmanuel Macron is to meet opposition figurehead Svetlana Tikhanovskaya on Tuesday.
Mr Macron is beginning a two-day trip to Lithuania, where Ms Tikhanovskaya took refuge after the disputed 9 August presidential election, which she says she won.
Why did Alexievich leave?
Svetlana Alexievich won the 2015 Nobel Prize for Literature "for her polyphonic writings, a monument to suffering and courage in our time".
She was also the last leading member of the opposition Co-ordination Council still in Belarus who had not been detained.
Speaking to Reuters, her aide, Tatiana Tyurina, said Ms Alexievich had left the country for treatment and also work reasons.
"She will return," the aide said.
Ms Tyurina said the writer would take part in a book fair in Sweden and an award ceremony in Sicily.
"Of course, the return will also depend on whether the authorities will allow her to return," Ms Tyurina added.
Earlier this month, European diplomats were photographed at Ms Alexievich's home in the capital, Minsk, after she said masked men had tried to break in.
What are the protests about?
The mass rally held on Sunday was the 50th day of protest over the election.
The electoral commission says Mr Lukashenko - in power since 1994 - won a sixth term with more than 80% of votes. Last week, he was inaugurated at an unannounced ceremony in Minsk.
But the opposition says he cheated and that it won the election with at least 60% of the vote.
The US and the 27 member states of the EU say they do not recognise Mr Lukashenko as the legitimate president.