BRUSSELS, Oct 4 (Reuters) - The European Union’s top officials expressed serious concern on Thursday about a cyber attack carried out against the Organisation for the Prohibition of Chemical Weapons (OPCW) in The Hague by Russia’s military intelligence service.

The head of the European Commission Jean-Claude Juncker, the chairman of EU leaders Donald Tusk and the EU’s High Representative for Foreign Affairs Federica Mogherini said in a statement that the “aggressive act demonstrated contempt for the solemn purpose of the OPCW”.

“We deplore such actions, which undermine international law and international institutions,” they said.

“The EU will continue to strengthen the resilience of its institutions and those of its member states, and international partners and organisations in the digital domain,” they said. (Reporting By Jan Strupczewski; editing by Philip Blenkinsop)