Berlin's Justice Ministry on Friday approved a request from Moscow for legal assistance in the investigation of the suspected poisoning of opposition leader Alexei Navalny.

Germany has tasked state prosecutors with working with Russian authorities, officials said. The work will also include providing information on the dissident's state of health "subject to his consent."

Separately, Russian police said Friday they were seeking to question Navalny in person in Berlin, where he is recovering in hospital from his ordeal.

The proposal is all but certain to be brushed off by Germany, which says the fierce critic of Russian President Vladimir Putin was poisoned with the banned nerve agent, Novichok.

Navalny was airlifted to Berlin last month after falling ill on a flight from Siberia to Moscow.

The Russian hospital that initially treated him said there was no evidence he was poisoned.

In a statement, Russia's Interior Ministry in Siberia said it wanted to send its own team to work alongside German investigators on the case, after reports that Navalny had emerged from a coma.

The statement said Russia wanted its officers to be present as "German colleagues carry out investigative activities with Navalny, medics and experts" and ask "clarifying and additional questions."

Read more: Angela Merkel says Novichok poisoning of Russia’s Navalny was attempted murder

Navalny interview requested

"This request will include an application for the possible presence of Russian internal affairs investigators... and a Russian specialist when German colleagues are conducting investigations with Navalny, doctors and experts," the ministry said in a statement.

Berlin said Friday it had received no such request so far.

Russia is yet to open a criminal investigation into the incident but has called for German officials to help in a preliminary probe. On Friday, Berlin accepted a request by Moscow for further information about the alleged poisoning.

The public prosecutor's office in Berlin said it had been instructed by state authorities in the German capital to provide legal assistance and information on Navalny's health to Moscow.

Navalny must however agree to this, the prosecutor said in a tweet.

The former lawyer has organized several series of protests against Putin, whom he accuses of perpetuating widespread corruption.

The novichok nerve agent used poison Navalny was "harder" than previous forms, Germany's Der Spiegel news magazine reported on Friday, citing an anonymous source in Germany's foreign intelligence agency.

Read more: Opinion: Germany unlikely to pressure Russia on reported poisoning

Sanctions pressure grows

The alleged poisoning has fueled pressure on the United States and the European Union to step up sanctions against Moscow.

Some senior German politicians have said Berlin shouldrevoke support for Nord Stream 2, a big gas pipeline from Russia to Germany set to open next year.

Such a move would amount to the most drastic economic penalty the West has imposed on Russia since the Soviet era.

Kremlin spokesman Dmitry Peskov said Moscow resented foreign pressure over the case. It had investigated the incident but did not have evidence that would lead to a criminal case, he said.

mm/sms (AP, AFP, dpa, Reuters)