They remain in critical condition in a hospital.
Labour Party leader Jeremy Corbyn says in a newspaper column that politicians must not "rush way ahead of the evidence being gathered by the police".
Yulia Skripal flew to London from Russian Federation on March 3, according to counter-terrorism police.
"On March 4, a weapon so horrific that it had been banned from the use in war, had been used on the United Kingdom's soil, in a reckless act carried out by people who disregarded the sanctity of human life", a UK representative told the Conference.
Tensions with Moscow are growing before Russia's presidential election Sunday, after a nerve agent attack in Britain on a Russian ex-spy.
After imposing new sanctions against Russia and accusing the country of carrying out a suspicious chemical attack against a former Russian double agent in Britain, the United States has hinted at more and tougher measures against Moscow.
Explaining the sanctions via a teleconference, several senior US officials said further sanctions and measures will come, according to the White House.
Moscow will expel British diplomats in response to London's move to kick out 23 staff at the Russian embassy in London over the poisoning of ex-double agent Sergei Skripal, Russian Foreign Minister Sergei Lavrov said Friday.
The Trump administration announced sanctions Thursday on 19 Russians and five companies accused of meddling in the 2016 USA election.
Lavrov was speaking in the Kazakh capital Astana following talks on Syria with the foreign ministers of Iran and Turkey.
Lavrov on Friday accused Britain of violating global law and criticized Britain's defense minister for what he called "uneducated" comments about Russian Federation.
Britain, the United States, Germany and France jointly called on Russian Federation on Thursday to explain how the toxin came to be used on British soil.
Sergei and Yulia were found slumped unconscious on a bench outside a shopping mall in Salisbury, southwest of London on March 4.
The Geneva-based Conference on Disarmament on Thursday heard an update by Britain on the March 4 incident in Salisbury in which Britain said a military-grade nerve agent Novichok developed by Russian Federation had been used, Xinhua reported.