"So Boris Johnson seems to have completely exceeded the information that he had been given and told the world in categorical terms what he believed had happened. And it’s not backed up by the evidence he claimed to have got from Porton Down in the first place. Boris Johnson needs to answer some questions… Where does that leave the foreign secretary? Egg on his face for the statement he made," Corbyn told the Sky News broadcaster.
On Tuesday, Gary Aitkenhead, chief executive of the Defence Science and Technology Laboratory (DSTL) at Porton Down said that the lab had identified the substance used to poison former double agent Skripal as Novichok, but could not prove that it was made in Russia or to determine its country of origin.
The UK foreign secretary in response has condemned Corbyn for choosing "to side with the Russian spin machine."
"It is lamentable that Jeremy Corbyn is now playing Russia’s game and trying to discredit the UK over Salisbury attack," Johnson wrote on Twitter.
The official added that Russia "has a motive for targeting" Skripal and noted that 28 countries are "convinced" by the UK accusations.
Soon after the incident, the United Kingdom announced the expulsion of 23 Russian diplomatic workers. Over 25 countries have since expelled Russian diplomats "in solidarity" with London. Moscow has denied having any role in the poisoning, pointing to the lack of evidence provided by London to substantiate its accusations.