Alexei Navalny’s associates say that the nerve agent used to poison the Russian opposition leader was found on a water bottle in his hotel room shortly after he fell ill on the plane back to Moscow. Mr Navalny, President Vladimir Putin’s most prominent critic, was on a ventilator in a medically induced coma for weeks after falling suddenly ill on a flight from Siberia to Moscow last month. Several European laboratories independently confirmed that the top Kremlin critic had been poisoned with the Soviet-era nerve agent Novichok, previously used in the attack on former Russian spy Sergei Skripal in Salisbury. Mr Navalny’s team revealed in a social media post on Thursday that the poison was found on one of the free water bottles that his colleagues retrieved from his hotel in the Siberian city of Tomsk shortly after Mr Navalny became unwell on the plane. The 44-year-old opposition leader was in Tomsk with his team in mid-August filming a video for an anti-corruption investigation and headed back to Moscow while some of his colleagues stayed behind, according to his spokeswoman Kira Yarmysh. Mr Navalny’s colleagues went to his room as soon as they heard that he lost consciousness on the plane that later had to make an emergency landing. He was treated by Russian doctors in Siberia for two days before his medical evacuation to Germany.