The Foreign Ministry summoned the Russian ambassador, Sergey Razov, after the sting operation late Tuesday caught the two in what police said was a “clandestine operation” to exchange the goods.
The OPCW also made no assessment of who was to blame for the March 4 attack on former Russian spy Sergei Skripal, which also affected his daughter Yulia and a local policeman.
OPCW confirmed that the chemical used was "of high purity", without mentioning the exact name of the substance which will be reserved for the complete classified report it has prepared.
Yulia Skripal, the daughter of former Russian spy Sergei Skripal who was poisoned in March, has turned down an offer of help from the Russian Embassy, according to police.
The poisoning has chilled relations between Russia and the West, producing a wave of diplomatic expulsions unseen even at the height of the Cold War.
Britain blames Russia for the March 4 poisoning of former double agent Sergei Skripal and his daughter Yulia, a charge the Kremlin furiously denies.
The diplomatic fallout between Russia and Britain over the poisoning of Sergei Skripal took another bizarre turn as Moscow complained of a lack of information about the former double agent's pets.
Putin urged 'common sense' to prevail in the spy poisoning crisis as London and Moscow faced off in a tense meeting at the world's chemical weapons watchdog.
head of Russia's SVR foreign intelligence agency said Wednesday the poisoning of Russian former spy Sergei Skripal in Britain was a "grotesque provocation" by the UK and US.
British military facility analysing the Novichok nerve agent used to poison Russian spy Sergei Skripal and his daughter said it has 'not identified the precise source' of the substance.
Skripal and his 33-year-old daughter were on March 4 exposed to a military-grade nerve agent in the British city of Salisbury.
In Washington, the State Department said there was no justification for the Russian move and that the United States "reserves the right to respond."
In all, more than 150 Russian diplomats have been ordered out of the US, EU members, NATO countries and other nations in coordinated action against Moscow.
Investigators had earlier sealed off the bench where the Skripals were found, a pub and restaurant the pair visited, and the grave of the former spy's wife.
Describing them as "intelligence officers", US ordered closure of the country's consulate in Seattle over the use of nerve agent allegedly by Moscow against a former Russian spy in the UK.