Foreign Secretary Boris Johnson and later Prime Minister Theresa May praised the British for their "unconditional solidarity" with Britain in the Scripal case.
As he entered the General Affairs Council in Brussels, the British Foreign Secretary commented that Russia could not deceive anyone and that it was "hiding the needle of truth in the straw of lies".
Meanwhile, a team of experts from the International Organization for the Prohibition of Chemical Weapons has arrived in Salisbury, which Britain has called for to confirm the findings involving Russia in the use of the chemical "Novitsok".
On Tuesday, Theresa May will chair a new meeting of the National Security Council.
Proof or apologize, says the Kremlin
The Kremlin has said London should either back up its claims that Russia was behind the poisoning of former double agent Sergei Skripal and his daughter in Britain, or apologize "sooner or later."
Britain has blamed Russia for using the neurotoxic agent Novitsok, made during the Soviet Union, to poison Sergei Skripal and his daughter Julia.
Kremlin spokesman Dmitry Peshkov told reporters that Britain's allegations were "difficult to explain; they are baseless and defamatory". Russian President Vladimir Putin said on Sunday that it was nonsense to believe that Moscow was responsible for the attack. British Foreign Secretary Boris Johnson said today that Russia's denials were "increasingly absurd".