Latest: Russia's ambassador has accused the British authorities of destroying evidence in the Salisbury nerve agent attack.

Russian officials have requested a meeting with the UK's Foreign Secretary Boris Johnson to discuss the nerve agent attack on former double-agent Sergei Skripal and his daughter Yulia.

Speculation is mounting that Sergei Skripal and his daughter Yulia could be able to offer officers investigating the Salisbury nerve agent attack missing clues as the pair continue to recover.

Russia has warned Britain is "playing with fire and will be sorry" over the Salisbury poisoning as it emerged Yulia Skripal's strength is "growing daily".

The current spat between the UK and Russia is like a game of poker. At first sight, Britain appears to be playing a strong hand, convincing its allies — Ireland included — that the Russian government is behind the attempted assassination of ex-spy Sergei Skripal and his daughter Yulia.

The head of the UK's Porton Down military research facility has said his scientists have not verified that the nerve agent used in Salisbury came from Russia.

The Kremlin has denied a claim that poisoned former Russian double agent Sergei Skripal wrote to Vladimir Putin asking to be pardoned and to be able to visit his home country.

Hundreds of diners and pub-goers have been offered compensation for dry-clean only clothing that may have come into contact with the nerve agent used to attack Sergei Skripal and his daughter.

The police officer exposed to the Novichok nerve agent after the Salisbury poisoning has said "normal life for me will probably never be the same" after he was discharged from hospital.

Russia has been stockpiling the nerve agent used in the Salisbury spy attack for a decade, Boris Johnson has claimed.

Latest: Britain has asked the international chemical weapons watchdog to verify its findings that Moscow is behind the nerve agent attack in Salisbury.

Latest: Russia will refuse to meet Theresa May's midnight deadline unless Britain agrees to send Moscow samples of the nerve agent used to poison Sergei Skripal.

Foreign Secretary Boris Johnson has welcomed international support over the Salisbury nerve agent poisoning as the deadline for Russia to provide a "convincing explanation" creeps closer.

Latest: British Prime Minister Theresa May has told the UK's House of Commons that it is "highly likely" that Russia is responsible for the nerve agent attack on Sergei Skripal and his daughter Yulia.

Two women, a Vietnamese and an Indonesian, have been arrested for allegedly coating their hands with the nerve agent VX and wiping them on the face of Kim Jong Nam at Kuala Lumpur's airport.