A prominent critic of Vladimir Putin who was rushed to hospital with organ failure had been planning to travel to the United States later that day, his wife has revealed.

Vladimir Kara-Murza, who works for pro-democracy group Open Russia, was taken to an intensive care unit in Moscow on 2 February and remains in a “grave” condition.

The 34-year-old had spent the night at his in-laws’ home where his wife and two children live, when he fell ill hours before they were due to fly to Washington DC.

In 2015, the activist and journalist spent two months in hospitals after surviving a suspected poisoning.

Evgenia, his wife, told The Independent: “They are symptoms that resemble those from two years ago. My parents called me and I asked the ambulance to take my husband to the same medical team he was with last time.

“They were supposed to fly to Washington together that same day.”

The last time Ms Kara-Murza spoke to her husband was the night he became ill.

“He spoke to me at the onset of his symptoms,” she said. “He called me to say he was not feeling right, that he had an accelerated heart rate and trouble breathing.”

His medical team have diagnosed an “acute intoxication by an unidentified substance”.

Mr Kara-Murza had been travelling around Russia in recent weeks to conduct screenings of his documentary about his friend Boris Nemtsov, a liberal opposition politician who was assassinated near the Kremlin in 2015.

The day before falling ill, he had paid tribute to Nemtsov on Facebook.

No definite cause was ever established for Mr Kara-Murza’s illness in 2015, but both he and his wife believe it was intentional poisoning.

“There are unfortunately many people very irritated with my husband’s activities, so it’s very hard to determine who exactly could be behind both attacks, or one of them,” Ms Kara-Murza said.

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Speaking in 2016, Mr Kara-Murza said he had “no doubt” his ordeal two years ago was a “deliberate poisoning aimed to kill”, and that it was politically motivated.

“I was a healthy 33-year-old man. Suddenly, when all of your major organs shut down within 24 hours, one after another – that doesn't just happen,” he told RFE.