Berlin (AFP) -
Germany said Wednesday that Russian opposition leader Alexei Navalny was poisoned with a Novichok nerve agent, the same type of chemical used in Britain against ex-double agent Sergei Skripal, dramatically ramping up tensions with Moscow.
Tests carried out by the German army on Navalny, who is being treated in a Berlin hospital, have provided 'unequivocal evidence of a chemical nerve agent from the Novichok family,' German government spokesman Steffen Seibert said in a statement.
'It is a shocking event that Alexei Navalny has become the victim of an attack with a chemical nerve agent in Russia.
'The government condemns this attack in the strongest terms. The Russian government is urgently requested to provide clarifications over the incident,' he added.
Foreign Minister Heiko Maas said Germany had called in Russia's ambassador to demand answers on the case.
Navalny, 44, fell ill after boarding a plane in Siberia last month. He was initially treated in a local hospital before being flown to Berlin for treatment.
The nerve agent Novichok is a military-grade poison that was developed by the Soviet government towards the end of the Cold War and can be deployed in an ultra-fine powder, liquid or vapour.
The Charite hospital last week reported 'some improvement' in Navalny's condition but he nevertheless remains in a medically induced coma and on a ventilator.
The severity of the poisoning meant that it was too early to determine potential long-term effects, the hospital warned.
Charite doctors said they believed the anti-corruption campaigner was poisoned with a substance that inhibits the cholinesterase enzyme, a feature of nerve agents.
- Skripal, Litvinenko poisoning -
The case has drawn parallels with two suspected Kremlin-linked poisonings in Britain.
In 2006, President Vladimir Putin was blamed for the radiation poisoning death of former KGB agent Alexander Litvinenko in the British capital.
In 2018, the Kremlin was also accused of being behind the attempted murder of ex-double agent Sergei Skripal in Salisbury, southwest England, using a Novichok nerve agent.
'Only the state (FSB, GRU) can use Novichok. This is beyond any reasonable doubt,' Ivan Zhdanov, the director of Navalny's Anti-Corruption Foundation, said on Twitter on Wednesday, referring to the FSB internal security and GRU military intelligence services.
The German government said it would inform NATO and EU partners over its findings and seek a joint reaction on the case.
Navalny's allies say he may have been poisoned by a cup of tea he drank at Tomsk airport in Siberia.
But the Russian doctors who first treated Navalny said their tests did not find any toxic substances, and the Kremlin has rejected international calls for an investigation.
On Wednesday, Kremlin spokesman Dmitry Peskov told state news agency Ria Novovsti that Russia had not been informed about the German government's latest findings.
Russia has for years drawn the anger of Western powers, from annexing Ukraine's Crimea to meddling in elections and backing Bashar al-Assad's government in Syria.
German Chancellor Angela Merkel has walked a fine line, stressing the importance of dialogue with Putin while making clear her disapproval of Russian moves on the world stage.
But Navalny's poisoning could further fray already tattered ties, coming after a murder in a central Berlin park in August last year which German prosecutors believe was ordered by Russia.
Merkel had also revealed in May that Russia had targeted her in hacking attacks, saying she had concrete proof of the 'outrageous' spying attempts.