SEATTLE — A group of hackers associated with Russian intelligence targeted civil society groups across Europe ahead of May elections there, Microsoft said on Tuesday.

The attacks, disclosed by Microsoft in a blog post, demonstrate the continuing spread of a broad online campaign aimed at disrupting real and potential political opponents of Russia’s president, Vladimir V. Putin. The company said it had found that hackers targeted more than 100 email accounts at think tanks and nongovernmental organizations that work on issues including election security, nuclear policy and foreign relations.

Microsoft didn’t address what country the attacks came from, but it blamed a group of hackers sometimes called Fancy Bear. Online security companies have identified Fancy Bear as a Russian group, and it is widely believed to be tied to Russian intelligence.

Fancy Bear was involved in the 2016 hacking of the Democratic National Committee in the United States, according to the party and security researchers. Last year, the American authorities indicted 12 Russian intelligence officers related to the hacks of the party headquarters and the Clinton presidential campaign.