Russian opposition leader Alexei Navalny is unconscious and in intensive care in hospital after apparently being poisoned, his spokeswoman has said.
Kira Yarmysh said Navalny was flying from Siberia to Moscow and his plane made an emergency landing after he fell ill.
"Alexei has toxic poisoning," she wrote on Twitter. "Alexei is now in intensive care."
Yarmysh said "We think that Alexei was poisoned with something mixed in his tea. That was the only thing he drank in the morning."
"Doctors say the poison was quickly absorbed through the hot liquid," she added.
Navalny is in the intensive care unit for toxicology patients in Omsk Emergency Hospital No. 1, the TASS state news agency confirmed.
The 44-year-old, known for his anti-corruption campaigns against top officials and outspoken criticism of President Vladimir Putin, has suffered physical attacks in the past.
He suffered chemical burns to his eye in 2017 when attackers threw green dye used as a disinfectant at his face outside his office.
Last year, Navalny was rushed to a hospital from prison where he was serving a sentence following an administrative arrest, with what his team said was suspected poisoning.
Doctors then said he had a severe allergic attack and discharged him back to prison the following day.
This article has been adapted from its original source.
