MOSCOW — Kremlin critic Alexei Navalny on Tuesday issued his first public statement since he was poisoned in Russia last month, writing on Instagram that he's able to breathe on his own after weeks on a ventilator.

His spokeswoman, meanwhile, confirmed that the opposition activist planned to return to Russia once he has recovered. “No other options were ever considered,” spokeswoman Kira Yarmysh wrote on Twitter. Neither Navalny nor Yarmysh indicated when he might return.

Navalny, 44, became ill during an Aug. 20 flight to Moscow from the Siberian city of Tomsk. By the time the plane made an emergency landing in nearby Omsk, Navalny was unconscious. Yarmysh said she suspected he was poisoned when he drank a cup of tea at the airport that morning.

Doctors in Omsk said they found no traces of poison when treating Navalny for two days, but the Berlin hospital attributed his condition to poison similar to the Soviet-era nerve agent Novichok, the same substance that Britain said Russian state security agents used on former Russian spy Sergei Skripal and his daughter in Salisbury, England, in 2018. On Monday, Germany said French and Swedish labs had confirmed its findings.

Charité hospital said Navalny regained consciousness last week after more than two weeks in a medically induced coma and he was able to get out of bed for short periods on Monday.

In his Instagram post Tuesday morning, Navalny is shown sitting up in bed beside his wife and two children and without breathing aids. “Hello, it’s Navalny,” the post says. “I miss you.”

“I still can’t do much, but yesterday I was able to breathe on my own all day long,” it continues. “I did not use any outside help, not even the simplest valve in my throat. I liked it very much. An amazing, underestimated by many process. I recommend it.”

Navalny’s allies have blamed Russian President Vladimir Putin’s government for Navalny’s poisoning, and an eventual return to Russia could be dangerous. Navalny, who was barred from running for president in 2018, has frequently been jailed and harassed. And this was not the first time he has been the victim of a toxic attack. In 2017, Navalny was attacked with an antiseptic green dye that damaged vision in one of his eyes.

Navalny’s team has published investigations exposing graft and wrongdoing by Russia’s elite. Over the past year, he has encouraged voters to back anti-Kremlin candidates as a message of discontent over Russia’s sagging economy and the unchecked power of Putin, who has the potential to stay in office until 2036 under constitutional changes approved this year.

Navalny-backed candidates won seats in regional elections over the weekend on city councils in Tomsk and Novosibirsk, the two cities Navalny visited on the trip just before he was poisoned. Putin’s United Russia party lost council majorities in both places.

Kremlin spokesman Dmitry Peskov, asked Tuesday about Navalny’s intention to return to the country, said “any citizen of the Russian Federation can leave Russia and return to Russia of his own volition.”

“If the health of this citizen of the Russian Federation improves, of course, this will make everyone glad,” Peskov said.

Despite calls from the West to investigate how Navalny was poisoned, Moscow has not opened a criminal case and has denied any official involvement. A Kremlin summary of a phone conversation Monday between Putin and French President Emmanuel Macron said: “The parties discussed in detail the situation surrounding the Alexei Navalny case. Putin, in turn, reiterated that the unsubstantiated and groundless accusations made against Russia in this context are inappropriate.”

Foreign Minister Sergei Lavrov told Russian state television Monday that “Western partners are glancing at us with arrogance, [as if they] have a right to doubt our correctness and professionalism.”

Sergei Naryshkin, director of Russia’s Foreign Intelligence Service, even hinted Tuesday that Germany could be responsible for Navalny’s poisoning. “It is a fact that the moment Alexei Navalny left the Russian territory, there were no toxins in his system,” he told reporters in Moscow. “Therefore, we have many questions for the German side.”

Germany’s justice ministry said last week it had consented to a request from Moscow for “mutual legal assistance” in Navalny’s case and had tasked Berlin state authorities with handling it.

Berlin state prosecutors confirmed that they had been asked to respond to the request and provide information on Navalny’s health, subject to his consent. State prosecutors have yet to meet with Navalny, according to a Berlin justice department spokesman. If Navalny consents, spokesman Sebastian Brux said, information on his medical condition will be passed on.

Loveday Morris in Berlin contributed to this report.