Paris (AFP) - Here are the main developments since the poisoning of a Russian former double agent in England, which London blames on Moscow.
- Poisoning in English city -
On March 4, spy Sergei Skripal, 66, and his daughter Yulia, 33, are found unconscious, slumped on a bench outside a shopping centre in Salisbury. They are now in critical condition in hospital.
Skripal is a former colonel in Russian military intelligence who was jailed for betraying agents to Britain's MI6 secret service. He left Russia for England in a 2010 spy swap.
On March 7 police say the father and daughter have been poisoned by a highly toxic nerve agent.
- London accuses indignant Moscow -
On March 12 British Prime Minister Theresa May says it is "highly likely Russia was responsible for the act", and Moscow could be directly to blame or may have "lost control" of the nerve agent.
She tells British lawmakers the military-grade nerve agent used was identified as belonging to a group known as Novichok ("Newcomer"), developed by the Soviet government towards the end of the Cold War.
Moscow rejects the claims as "provocation".
The US says it stands "in solidarity" with Britain.
On March 13 Russian Foreign Minister Sergei Lavrov says Moscow is "not guilty".
- Diplomatic sanctions -
On March 14 London says Moscow is "culpable" and it will expel 23 of the 59 Russian diplomats in the United Kingdom.
It also suspends high-level diplomatic contact with Moscow and will keep royals at home during the 2018 football World Cup.
Russia's foreign ministry promises early retaliation.
On March 15 in a rare joint declaration, Britain, France, Germany and the US say "there is no plausible alternative explanation" to Russian involvement and call on the Kremlin to provide "full and complete disclosure".
The 29-member NATO alliance expresses solidarity with Britain over what it calls the first offensive use of a nerve agent on the military alliance's territory since World War II.
On March 16 British Foreign Secretary Boris Johnson says it is "overwhelmingly likely" Russian President Vladimir Putin was behind the poisoning.
The Kremlin says the accusation is "unforgivable."
- Russian riposte -
On March 17, on the eve of the presidential election, Russia says it will expel 23 British diplomats and halt the activities of the British Council in Russia.
Re-elected to a fourth term on March 18, Putin calls the British accusations "drivel, rubbish".
On March 19 the Kremlin demands London either come up with proof of Russia's involvement or apologise.
The European Union offers Britain its "unqualified solidarity", but rules out new sanctions.
In a telephone call to newly-re-elected Putin, French President Emmanuel Macron urges him to firmly regain control of the fight against chemical weapons.
However, the subject is not raised in a call to Putin by US President Donald Trump.
- 'Lies and disinformation' -
On March 20 international weapons experts from the Organisation for the Prohibition of Chemical Weapons (OPCW) arrive in Britain to take samples of the toxic substance.
The same day, the expelled Russian diplomats leave the London embassy.
On March 21 the Russia foreign ministry calls a meeting of foreign diplomats to explain Moscow's view on the poisoning.
It says Britain either failed to protect Skripal from what it termed a "terrorist attack" or was itself behind the poisoning.
It criticises London's "Russophobia", while the British embassy says Moscow is spreading "lies and disinformation."