The European Union imposed chemical weapons sanctions on nine Russian and Syrian officials Monday, including the chief of the powerful GRU military intelligence agency.

Five of those targeted are linked to the Syria's Scientific Studies and Research Center (SSRC). The four Russians on the list are the two men accused of planting the nerve agent in Salisbury last March and their superiors, the head and deputy head of the GRU, Russia's military intelligence unit. "This decision contributes to the EU's efforts to counter the proliferation and use of chemical weapons which poses a serious threat to international security," the statement said, after a meeting of EU foreign ministers.

Russian agents have been blamed for the poisoning of former Russian spy Sergei Skripal and his daughter in the English city in March last year using the Soviet-developed nerve agent Novichok. The Salisbury attack, the first offensive use of chemical weapons in Europe since World War II, caused an international outcry and prompted a mass expulsion of Russian diplomats by Western nations. The Skripals survived the attack but a woman died in June after her partner picked up a discarded perfume bottle that British investigators believe was used to carry the Novichok. Moscow denies involvement in the poisoning and has offered numerous and varied alternative explanations and counter-accusations.