Foreign Secretary Dominic Raab was due to hold talks today with his German counterpart Heiko Maas on the West’s response to the attack on Mr Navalny, with gas sanctions against Russia already being mooted in Berlin.
Boris Johnson has condemned the poisoning as “outrageous”.
The Prime Minister’s official spokesman said today: “We are committed to working with Germany, our allies and international partners to demonstrate that there are severe consequences to the use of banned chemical weapons.
“The OPCW (Organisation for the Prohibition of Chemical Weapons) will also have an important role to play investigating this attempted murder.
“The internationally community must come together and use all of the tools at our disposal to hold the perpetrators accountable.”
He stopped short of directly blaming Russia for the attack, which Moscow’s denies being involved in.
But he added: “There are serious questions for the Russian government to answer and it must now explain what happened to Mr Navalny.”
The UK has offered Germany support from its experts given the knowledge they gained from dealing with the 2018 Novichok attack in Salibury on Russian former double agent Sergei Skripal and his daughter Yulia.
Earlier, a close ally of German Chancellor Angela Merkel raised the prospect of gas sanctions against Russia.
Norbert Roettgen, head of Germany’s parliamentary foreign affairs committee, said: “There must be a European response,” when asked if work on the NordStream 2 pipeline from Russia to Germany should stop in response to the attack on Mr Navalny.
“We must pursue hard politics, we must respond with the only language Putin understands – that is gas sales,” added Mr Roettgen, a member of Ms Merkel’s ruling CDU party.
European leaders have strongly condemned the poisoning of Mr Navalny, though there was silence yesterday from Donald Trump on the case.
Berlin said a military laboratory produced “unequivocal evidence” that he had been poisoned with Novichok, a nerve agent developed in Russia.
But the foreign ministry in Moscow said Germany’s assertion was not backed by evidence and the head of Russia’s foreign intelligence agency insisted it could not be excluded that Western special forces were behind the poisoning of Kremlin critic Mr Navalny.
Sergei Naryshkin, head of the agency, added that no traces of poison had been found by Russian doctors after Navalny fell ill in Siberia last month.
However, diplomats in the West had expected Russia to launch a disinformation campaign over the case.
Mr Navalny, 44, fell ill on a flight back to Moscow from Siberia on August 20 and is now in a coma in intensive care in a hospital in Berlin after activists arranged for him to be flown to Germany.
Mr Johnson tweeted yesterday: “The Russian government must now explain what happened to Mr Navalny – we will work with international partners to ensure justice is done.”
However, Sarah Bailey, the wife of Wiltshire Detective Sergeant Nick Bailey who almost died after he was exposed to Novichok while responding to the 2018 attacks in Salisbury, responded: “Justice would be nice. Actions speak louder than words.”
Det Sgt Bailey was the first person to enter the home of Mr Skripal after he and his daughter Yulia were found poisoned on a park bench in Salisbury.
He has spoken previously of “still trying to pick up the pieces” of his life after becoming seriously ill from the poisoning, and losing his family home and possessions due to contamination fears.
Mr Johnson, as Foreign Secretary in 2018, played a key role in the expulsion by more than 20 allied countries of more than 100 suspected Russian spies in response to the Salisbury poisonings.