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.” The F.S.B. is a successor agency to the Soviet-era K.G.B.

Mr. Gershkovich was detained in Yekaterinburg, a city about 900 miles east of Moscow in the Ural Mountains, according to Russian state-run news outlets, which reported the F.S.B. statement.

The Wall Street Journal said in a statement that it “vehemently denies the allegations from the F.S.B. and seeks the immediate release of our trusted and dedicated reporter, Evan Gershkovich. We stand in solidarity with Evan and his family.”

The U.S. Embassy in Moscow did not immediately comment on the report.

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

No Western journalist has been tried on espionage charges in Russia in recent years. The arrest of Mr. Gershkovich represented a significant escalation in Moscow’s hostilities toward foreign news organizations, many of which sharply curtailed their activities in Russia last year after harsh new laws in effect outlawed some forms of independent reporting after the invasion of Ukraine.

Several Western outlets temporarily removed their reporters from Russia in March 2022, citing the risk of prosecution for standard forms of news gathering. Since then, correspondents from some Western news organizations have continued to report out of Russia, albeit in smaller numbers than in previous years.

Mr. Gershkovich has worked for The Journal in Moscow since January 2022.Credit…Dimitar Dilkoff/Agence France-Presse — Getty Images

Mr. Gershkovich faces up to 20 years in prison under Russia’s criminal code. Espionage trials in Russia can take months and are typically conducted in secret.

Acquittals are virtually unheard-of. In past espionage cases, after a guilty verdict, Russia has sought an exchange for a Russian spy held in the West. In 2019, in exchange for two convicted Russian spies in Lithuania, Moscow freed a Norwegian man who had been held for 23 months on accusations of espionage.

The detention of Brittney Griner, an American W.N.B.A. star, on a minor drug charge in March 2022 set off a monthslong negotiation between Moscow and Washington for her release, culminating in a prisoner swap that freed a Russian arms dealer from U.S. custody. American officials have also pushed for the release of Paul Whelan, a former Marine who has been held since 2018 and sentenced to 16 years in Russian prison for what the United States considers sham espionage charges.

While Moscow was already cracking down on press freedom in the years leading up to the invasion of Ukraine, foreign correspondents continued to receive accreditation from the Russian Foreign Ministry and were generally able to operate freely.

The Journal recently named a new top editor, Emma Tucker, who now faces one of the most daunting challenges of a long career. In 2014, as deputy editor of The Times of London, Ms. Tucker was closely involved in an episode involving two of the British newspaper’s correspondents who had been kidnapped and detained in Syria. One of the journalists, Anthony Loyd, was shot twice in the leg, and the other, the photographer Jack Hill, was beaten up before the men were able to escape.

Victoria Kim contributed reporting.