The incident happened at the Bruzgi checkpoint, according to the ONT (All-National Television) state broadcaster, which posted on its Telegram channel photos of an man who had dark red spots and blisters all over his head, neck and hands.
The Belarus 1 state TV channel demonstrated a video of medical workers treating a man with burns and a swollen eyelid.
The Belarusian Belta news agency also posted pictures of the injured man on its Telegram-channel, and reported that the chemicals used by Polish security forces cause eye irritation and chemical burns.
On Tuesday, Igor Malyk, deputy head of the radiation, chemical and biological protection and ecology department of the General Staff of the Belarusian Armed Forces, said that Polish security forces had used specialized toxic chemicals against migrants. The Belarusian Investigative Committee began an investigation into the case.