A member of the Presidium of the Belarusian opposition's Coordination Council, Maria Kolesnikova, was detained while trying to illegally cross the state border with Ukraine, the Belarusian state-run news agency BelTA said.

"Maria Kolesnikova tried to illegally leave the territory of the Republic of Belarus but was detained on the border," BelTA said on Telegram.

Coordination Council members Anton Rodnenkov and Ivan Kravtsov left Belarus overnight, it said.

"At the moment, they are in Ukraine," BelTA said.

Meanwhile, official media outlets circulated a video that shows Coordination Council executive secretary Kravtsov announcing his decision to leave Belarus. The footage shows Kravtsov a few minutes before crossing the border, BelTA said on its Telegram channel on Tuesday.

"I've made a decision to leave the country. And now, we, including Maria Kolesnikova, will cross the border of the Republic of Belarus and will leave it for the time being," Kravtsov said in the video.

Official media outlets said earlier on Tuesday that Kolesnikova had been detained while trying to illegally leave Belarus.