The Russian authorities said on Thursday that they had detained an American journalist, Evan Gershkovich, a Wall Street Journal correspondent based in Moscow, accusing him of espionage.

The Federal Security Service, known by its Russian acronym F.S.B., said in a statement about Mr. Gershkovich that “on the instructions of the United States, he was collecting information about one of the enterprises of the Russian military-industrial complex, which constitute a state secret.”

He was detained in Yekaterinburg, a city in Russia’s Ural Mountains, according to Russian state-run news outlets, which reported the F.S.B. statement.

The U.S. Embassy in Moscow did not immediately comment on the report. A spokeswoman for Dow Jones, the publisher of the Journal, did not immediately respond to a request for comment.

Mr. Gershkovich has worked for the Journal in Moscow since January 2022 and previously reported in Russia for Agence France-Presse and The Moscow Times. Before that, he was a news assistant for The New York Times, based in New York.

Victoria Kim contributed reporting.