Facebook Inc. said it discovered a new group of accounts that engaged in coordinated political agitation and misinformation efforts ahead of November’s midterm elections, in an echo of Russian activities on the platform during the 2016 U.S. presidential campaign.

The social-media giant on Tuesday said it removed 32 pages and accounts from its main service and Instagram photo-sharing app that were created between March 2017 and May of this year. The pages and accounts—which include such names as “Aztlan Warriors,” “Black Elevation”...