BERLIN -- Russian dissident Alexei Navalny has been removed from his medically induced coma and is being weaned off mechanical ventilation, the Berlin hospital where he is being treated said on Monday.

A statement from the Charite hospital in the German capital said Navalny's condition "has improved" and that he is responding to verbal stimuli.

"It remains too early to gauge the potential long-term effects of his severe poisoning," the statement said.

Navalny, one of Russian President Vladimir Putin's most prominent critics, was transported to Germany in a comatose state on Aug. 22, two days after falling ill on a domestic Russian flight.

Germany has since said there is "unequivocal" evidence that the 44-year-old was the victim of a nerve agent attack, which Chancellor Angela Merkel described last week as an attempt "to silence him."

A toxicology report conducted at a special military laboratory in Germany found in Navalny's system traces of a chemical nerve agent from the Novichok group, a government spokesman said on Wednesday.

German Foreign Minister Heiko Maas then summoned Russian ambassador Sergei Nechayev in protest and called for a full and transparent investigation.

The Russian government denies any involvement in the poisoning.

The Russian attorney general has issued a request for legal assistance from Germany on the Navalny case. Maas told broadcaster ARD that his country had approved that request.

Merkel is not ruling anything out in terms of a potential response to the incident, including a possible reconsideration of Germany's Nord Stream 2 pipeline project with Russia, her spokesman said on Monday.

But Moscow must first answer serious questions about the Navalny incident, Steffen Seibert told reporters in Berlin.

Construction of the Nord Stream 2 pipeline is nearly complete. It would double Russian deliveries of natural gas via a Baltic Sea route to Germany, Europe's largest economy. The project, already criticized by the United States and some Eastern European countries, has come under increased scrutiny following the alleged attack on Navalny.

"Navalny is being used here as a political toy," Vladislav Belov, head of the Centre for German Studies at Moscow's Russian Academy of Sciences, said. "He's being used to stop Nord Stream 2."

Should that be the case, the traditionally good relationship between Germany and Russia would be affected -- but not beyond repair, Moscow-based economist Vladislav Inozemtsev told dpa.

"It would be a shame about the money, but (partially state-owned Russian gas company) Gazprom won't go broke because of it," he said. In that case Russia could send more gas through Ukraine to Europe, enriching Kiev in the process, Inozemtsev said.

In addition, the gas pipeline known as the "Power of Siberia" was laid last winter between Russia and China.

Dusseldorf energy firm Uniper, which is involved in Nord Stream 2, warned that the pipeline and liquid-gas terminals are "urgently needed to guarantee a secure, flexible and reasonably priced supply of natural gas to Europe."

There is also political opposition to stopping Nord Stream 2. The Social Democrats' (SPD) Manuela Schwesig, premier of the German state of Mecklenburg-Western Pomerania, warned that the pipeline is set to bring much-needed jobs to her region.