"Two independent laboratories, in France and Sweden, and the German Defense Special Laboratory have confirmed novitiate in and on my body," the regime critic wrote on his blog.
Navalny continues that he expects nothing more than explanations from the Russian side, but that he wants at least his clothes back.
They are "a very important proof", and the politician demands that they be "carefully packed in a bag and sent to me".
"Completely naked"
The opposition leader fell ill during a flight between Siberian Tomsk and Moscow on August 20.
The plane made an emergency landing and he was taken to a hospital in the city of Omsk, where the clothes he was traveling in were taken care of.
According to his blog post, he was handed over "completely naked" to the German ambulance plane which then took him to Berlin, where he is now being cared for.
Russian health authorities answer, however, that the hospital in Omsk has no clothes left.
- Investigating authorities seized the clothes as part of a preliminary investigation when Navalny was in Omsk, it is said according to regional authorities, writes the news agency Interfax.
And Dmitry Peskov, a spokesman for Russian President Vladimir Putin, is dismissive.
- With all due respect, we do not deal with clothes.
This is not our area, he answers according to Interfax when Russian media ask him to comment on Navalny's demands.
According to Peskov, it is rather Navalny's employees who hinder the investigation, as they have taken material from, among other places, his hotel rooms abroad.
Russia rejects all suspicions
According to Western laboratories, Navalny was poisoned by a nerve agent, probably from a bottle of water in his hotel room before the flight.
The poison is known from previous cases in which Russian intelligence agencies are accused of being involved.
Russia rejects all suspicions, casting doubt on whether Navalny was poisoned.