German Chancellor Angela Merkel has said that Russian opposition leader Alexei Navalny was the victim of an “attempted murder by poisoning” and the aim was to silence him

The Russian dissident is receiving treatment in Germany after he fell into a coma after being poisoned on a flight to Moscow.

Earlier today Ms Merkel's government he had been poisoned with novichok, the same chemical used in the Salisbury attack in the UK.

After that finding was announced Wednesday, Ms Merkel said there are “very serious questions that only the Russian government can answer and must answer.”

Mr Navalny, a politician and corruption investigator who is one of Russian president Vladimir Putin’s fiercest critics, fell ill on a flight back to Moscow from Siberia on Thursday August 20, and was taken to a hospital in the city of Omsk after the plane made an emergency landing.

He was later transferred to Berlin’s Charite hospital, where doctors last week said there were indications that he had been poisoned.

A spokesman for German chancellor Angela Merkel said test by the nation's military scientists revealed the presence of “a chemical nerve agent from the Novichok group.”

German Chancellor Angela Merkel said there were questions for the Russian state to answer

A Kremlin spokesman Dmitry Peskov last month rejected suggestions that the Kremlin was behind the attack.

He said: “These accusations absolutely cannot be true and are rather an empty noise.

“We do not intend to take it seriously.”

Boris Johnson joined those condemning the attack.

In a tweet he said: "It’s outrageous that a chemical weapon was used against Alexey Navalny.

"We have seen first-hand the deadly consequences of Novichok in the UK.

"The Russian government must now explain what happened to Mr Navalny – we will work with international partners to ensure justice is done."

According to the British government, novichok was used to poison former Russian spy Sergei Skripal and his daughter in Salisbury - an incident that led to the UK and its allies expelling Russian diplomats across the world.

Later another woman Dawn Sturgess became an unexpected victim after she reportedly found a bottle containing the substance and died.

Mr Skripal and his daughter both survived the attack.

Asked last month about the attack Boris Johnson said the poisoning of Alexei Navalny was “the most extraordinary thing”.

The Prime Minister told reporters: “We have had poisonings of people who have fallen out with the Russian regime and who have left Russia, we are used to – we saw what happened with Alexander Litvinenko, what happened to Sergei and Yulia Skripal in our country.

Russia has said it is not credible to claim it is involved in the attack

“We now have the most extraordinary thing, which is perhaps the leading domestic opponent of Vladimir Putin being poisoned in Germany.”

Mr Johnson continued: “You really have to ask yourself what has gone on here and I think what we want to see is a full, thorough, transparent investigation into the poisoning of Alexei Navalny and those who are responsible must be held to account and must be brought to justice.”

Doctors at the facility in Siberia where Mr Navaly was initially treated claim they ruled out poisoning.