British Foreign Secretary Boris Johnson has said the the Kremlin “must give answers” after the worlds chemical arms watchdog on Thursday confirmed that Sergei Skripal and his daughter Yulia were poisoned with a "high purity" strain of Novichok nerve agent in Salisbury. Samples tested by the Organisation for the Prohibition of Chemical Weapons (OPCW) "confirm the findings of the United Kingdom relating to the identity of the toxic chemical that was used in Salisbury", it said. OPCW collected its own samples in the city of Salisbury at Britains request. The watchdog however, made no assessment of who was to blame for the March 4 attack, AFP reported. Johnson said: "There can be no doubt what was used and there remains no alternative explanation about who was responsible. "Only Russia has the means, motive and record," he added. Russia has previously denied possessing the nerve agent Britain says was used while President Vladimir Putin has said "it was nonsense to think Moscow would have poisoned Skripal and his daughter," according to Reuters. Yulia was visiting from Russia when the poison attack took place. Despite initial doubts that they would not survive, Yulia Skripal was released from hospital to an undisclosed location on Monday. she said in a statement, after leaving the hospital, that she was suffering from the effects of the poisoning, while her father remained seriously ill . Reuters reported that she was declining an offer of assistance from the Russian Embassy.