Kolesnikova was sentenced to 11 years in prison last year.
ADVERTISEMENTBelarus political prisoner Maria Kolesnikova has been hospitalised in an intensive care unit, according to the Telegram channel of another opposition politician.
The political activist was first hospitalised in the city of Gomel yesterday, and her lawyer has not been able to see her, former presidential candidate Viktor Babariko said on Telegram.
Kolesnikova, who was a key figure in the opposition presidential campaign against Belarusian strongman Alexander Lukashenko in 2020, was sentenced to 11 years in prison last year.
She previously worked with the campaign of Babariko, who was stopped from registering after being arrested on charges of bribery.
Kolesnikova had faced charges of harming national security when she was detained in September 2020 after resisting authorities' attempt to force her into exile.
Belarus' opposition leader Sviatlana Tsikhanouskaya said that the news about Kolesnikova was "extremely worrying".
"Maria Kalesnikava has been hospitalised in intensive care for unknown reasons," Tsikhanouskaya tweeted.
"Her lawyer has not been allowed to see her. Recently she was placed in a punishment cell. We need information about her condition & must assure that she gets proper help."
Babariko said that Kolesnikova's lawyer was not allowed to see her for "the third time in a row" on Tuesday.
Along with Tsikhanouskaya and Veronika Tsepkalo, Kolesnikova was one of the three women leading the movement to beat Lukashenko during the August 9, 2020, presidential election.
The election, which Lukashenko claimed he won, led to a series of mass protests in the country that authorities responded to with a violent crackdown.