The European Union is imposing sanctions on Russians blamed for a nerve agent attack in Britain and a Syrian research center as the bloc steps up its action against the use of chemical weapons.

EU foreign ministers on Monday slapped travel bans and asset freezes on nine people and on Syria's Scientific Studies and Research Center.

Five of those targeted are linked to the Syrian center's activities. 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.

The ministers said in a statement that the sanctions move "contributes to the EU's efforts to counter the proliferation and use of chemical weapons, which poses a serious threat to international security."