Colleagues of Alexei Navalny have revealed a nerve agent used to poison him was found on a water bottle inside his hotel room. The Russia opposition figure fell ill on a flight to Moscow.

The discovery of the alleged laced water bottle suggests Navalny was poisoned in the Siberian city of Tomskthere - and not at the airport as initially thought, his associates said. Navalny's associates had previously said they suspected tea he drank at the Tomsk airport contained poison.

Navalny was flown to Germany shortly after he fell ill where doctors induced him into a coma for more than two weeks as he was administered with an antidote at the Charite Hospital in Berlin.

Based on laboratory findings from Sweden, Germany and France, Navalny was poisoned by a nerve agent called novichok - a lethal toxin developed covertly by the Soviet military and used to poison former Russian double agent Sergey Skripal in Britain in 2018. Russian authorities have denied this and said solid proof must be presented.

In a Thursday interview with ABC News, Georgy Alburov - a member of Navalny's Anticorruption Foundation - said "it was obvious from the very beginning that Navalny had been poisoned." Alburov said they decided to gather the things even if there's "a microscopic chance it could be useful." Navalny's team said it was clear the case wouldn't be investigated in Russia.

But Alburov said the amount of nerve agent found on the water bottle was so small it couldn't contain the poison itself. Alburov discounted the possibility that the poison could have been in the water he had drunk. "No, in the water, no way," he said. The bottle had a small volume of the nerve agent but there were enough traces that Navalny had touched the bottle.