Putin critic Alexei Navalny hospitalized after suspected poisoning

Yarmysh said Navalny was flying back to Moscow when he started sweating.

She told Echo Moskvy radio station that Navalny asked her to talk to him so that he could "focus on the sound of a voice."

He then went to the washroom and fell unconscious, she said, adding that the plane made an emergency landing in Omsk.

"[Navalny] is in a coma in grave condition," Yarmysh said, "Doctors are saying the toxin was absorbed quicker with hot liquid."

She added that Navalny's team called police to the hospital.

Russia's state news agency Tass quoted the chief doctor of the hospital where Navalny is being treated as saying that the politician is in a grave condition.

Yarmysh said Navalny must have been poisoned from the tea he had consumed earlier in the day.

She said she suspected that the poisoning is connected to this year's election campaign.

A lawyer with Navalny's foundation, Vyacheslav Gimadi, said the team has requested Russia's Investigative Committee for a criminal probe into the incident.

Gimadi said the poisoning is linked to Navalny's political activity.

Navalny's Foundation for Fighting Corruption has been targeting corrupt government officials.

However, last month, the foundation had to be shut after being slapped with a lawsuit by Yevgeny Prigozhin, a businessman with links to the President.

The anti-corruption campaigner has been frequently detained by law enforcement.

He has also been pushing up candidates in regional election candidates against Russia's ruling party.

In 2017, several men threw antiseptic in Navalny's face, damaging one eye.

Last year, while serving time in prison due to an administrative arrest, he had been rushed to the hospital after a suspected poisoning.

Doctors said that he had had a severe allergic attack.

He was discharged from the hospital and sent back to prison the next day.