Russian opposition leader Alexei Navalny's health has improved so that he is now able to leave his bed briefly, the Berlin hospital treating him said Monday, while Germany announced that French and Swedish labs have confirmed its findings that he was poisoned with the Soviet-era nerve agent Novichok.

Navalny, the most prominent opponent of Russian President Vladimir Putin, was flown to Germany two days after falling ill on Aug. 20 on a domestic flight in Russia and is being treated at Berlin's Charite hospital. Berlin has demanded that Russia investigate the case.

The Charite said Navalny has now been “successfully removed from mechanical ventilation.” “He is currently undergoing mobilization and is able to leave his bed for short periods of time,” it added.

Monday's statement didn't address the long-term outlook for the 44-year-old Russian politician and anti-corruption investigator. Doctors have cautioned that even though Navalny is recovering well, long-term health problems from the poisoning cannot be ruled out.

The Kremlin has bristled at calls from German Chancellor Angela Merkel and other world leaders for Russia to answer questions about the poisoning, denying any official involvement and accusing the West of trying to smear Moscow.

Earlier Monday, the German government said tests by labs in France and Sweden had backed up earlier findings by a German military lab that Navalny was poisoned with Novichok, the same class of Soviet-era agent that British authorities said was used on former Russian spy Sergei Skripal and his daughter in Salisbury, England, in 2018.

The Hague-based Organization for the Prohibition of Chemical Weapons also is taking steps to have samples from Navalny tested at its reference laboratories, German government spokesman Steffen Seibert said.

He said Germany had asked France and Sweden for an independent examination of the findings. German officials said labs in both countries, as well as the OPCW, took their own new samples from Navalny.

“In efforts separate from the OPCW examinations, which are still ongoing, three laboratories have meanwhile independently of one another presented proof that Mr. Navalny's poisoning was caused by a nerve agent from the Novichok group,” Seibert said.

“We once again call on Russia to make a statement on the incident,” he added. “We are closely consulting with our European partners regarding possible next steps.”

Seibert wouldn't identify the specialist French and Swedish labs. But the head of the Swedish Defence Research Agency, Asa Scott, told Swedish news agency TT: “We can confirm that we see the same results as the German laboratory, that is, that there is no doubt that it is about these substances.” French President Emmanuel Macron expressed his “deep concern over the criminal act” that targeted Navalny during a phone call with Putin on Monday, Macron's office said.

Macron confirmed that France reached the same conclusions as its European partners on the poisoning, according to the statement.

“A clarification is needed from Russia within the framework of a credible and transparent investigation,” it added.

The Kremlin said Putin in the call “underlined the impropriety of unfounded accusations against the Russian side” and emphasized Russia's demand for Germany to hand over Navalny's analyses and samples to Russian experts. Putin also called for joint work on the case by German and Russian doctors.

Russian authorities have prodded Germany to share the evidence that led it to conclude “without doubt” that Navalny was poisoned with Novichok. Berlin has rejected suggestions from Moscow that it is dragging its heels.

Asked why no samples from Navalny have been given to Russia, German Foreign Ministry spokeswoman Maria Adebahr replied that “Mr. Navalny was in Russian treatment in a hospital for 48 hours.” Once he became ill, Navalny was treated at a hospital in the Siberian city of Omsk, where Russian doctors said no evidence of poisoning could be found and claimed he was too unstable to be transferred.

A German charity sent a medical evacuation plane to bring him to Berlin for treatment, which it did after German doctors said he was stable enough to be moved.

“There are samples from Mr. Navalny on the Russian side,” Adebahr said. “The Russian side is called on, even after three independent labs have established the result, to explain itself, and Russia has ... all the information and all the samples it needs for an analysis.” Navalny was kept in an induced coma for more than a week as he was treated with an antidote before hospital officials said a week ago that his condition had improved enough for him to be brought out of it.