WASHINGTON/LONDON, July 12 (Reuters) - Chinese state-linked hackers since May have secretly accessed email accounts at around 25 organizations, including U.S. government accounts, in a stealthy cyberespionage campaign, Microsoft (MSFT.O) and U.S. officials said on Wednesday. Microsoft did not say which organizations or governments had been affected, but added that the hacking group involved primarily targets entities in Western Europe. White House National Security Council spokesman Adam Hodge said an intrusion in Microsoft's cloud security "affected unclassified systems," without elaborating. The State Department "detected anomalous activity" and "took immediate steps to secure our systems," a department spokesperson said in a statement. Private sector cybersecurity experts have said newly discovered hacking activity shows how Chinese groups are improving their cyber capabilities.

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Persons: Jake Sullivan, ABC's, Adam Hodge, Hodge, John Hultquist, Will Dunham Organizations: WASHINGTON, Microsoft, White House, U.S . State Department, ., White, National Security, The State Department, U.S, Thomson Locations: LONDON, U.S, United States, Western Europe, China's, London, China