"Many trails point to the fact that Russian Federation is responsible", Merkel said just before talks in Paris with French President Emmanuel Macron where they were expected to discuss an appropriate response to the attack.
"Our quarrel is with Putin's Kremlin, and with his decision - and we think it overwhelmingly likely that it was his decision - to direct the use of a nerve agent on the streets of the United Kingdom, on the streets of Europe for the first time since the second world war", Johnson said.
Russian Foreign Ministry spokeswoman Maria Zakharova denied that Russia or the Soviet Union had ever developed Novichok, the class of nerve agent that Britain says was used to poison the Skripals.
The Russian Embassy in London is receiving threats targeting diplomats, Ambassador Alexander Yakovenko told Rossiya 24 television on Thursday.
A British policeman was also poisoned when he went to help them and remains in a serious but stable condition.
Moscow has rejected a British ultimatum to explain why a Soviet-developed toxin was allegedly used to poison a former Russian spy on British soil, until the United Kingdom hands over samples of the nerve agent.
The Government is preparing further moves against Russian Federation following a day of tit-for-tat action over the poisoning of former spy Sergei Skripal.
Earlier in the day, Washington slapped sanctions on Russian individuals and entities for alleged USA election meddling and cyber attacks but put off targeting oligarchs and government officials close to Putin, prompting US lawmakers in both parties to say Trump needs to do much more.
Russian Federation demanded that Britain hand over samples of the nerve agent for analysis in Moscow and suggested that if Britain was able to identify the chemical, it must also be able to produce it. Britain said the Russians being expelled were undeclared intelligence officers. May also said her government will cancel all high-level bilateral contacts with Russian Federation, which denies any involvement in the poisoning.
Authorities in Russia are reportedly set to expel British diplomats in retaliation for UK's Prime Minister Theresa May's decision to kick out 23 Russian diplomats over the nerve-agent attack on former spy Sergei Skripal and his 33-year-old daughter Yulia.
In comments to reporters after he left the Foreign Ministry, Bristow said the crisis had arisen because of "the attempted murder of two people using a chemical weapon developed in Russian Federation and not declared by Russian Federation".
More: Novichok: What is Russia's risky poison used in ex-spy Sergei Skripal's case?
Putin, a former KGB spy who is poised to win a fourth term in an election on Sunday, has so far only said publicly that Britain should get to the bottom of what has happened.
"The British side is warned that in case of further unfriendly actions against Russia, the Russian side reserves the right to take further retaliatory measures", the ministry said.
"The accusations are unsubstantiated, moreover, these accusations surfaced even before any information on the used substance could appear", he said. "Crimea is part of Ukraine and our Crimea-related sanctions will remain in place until Russian Federation returns control of the peninsula to Ukraine", she said in a statement on March 14.
"It sounds to me like they believe it was Russian Federation and I would certainly take that finding as fact", Trump told reporters outside the White House.
"We call on Russian Federation to live up to its responsibilities as a member of the UN Security Council to uphold global peace and security", they said.
"If we don't take immediate concrete measures to address this now, Salisbury will not be the last place we see chemical weapons used", Haley added,"They could be used here in NY or in cities of any country that sits on this council". She added, "They could be used here in NY or in cities of any country that sits on this council".
Haley called the crisis a "defining moment" for the U.N. and said the United States was solidly behind Britain.