MOSCOW • Russia’s security service arrested an American reporter for The Wall Street Journal on espionage charges, the first time a U.S. correspondent has been detained on spying accusations since the Cold War. The newspaper denied the allegations and demanded his release.

Evan Gershkovich was detained in the city of Yekaterinburg while allegedly trying to obtain classified information, the Federal Security Service, known by the acronym FSB, said Thursday.

The service, which is the top domestic security agency and main successor to the Soviet-era KGB, alleged that Gershkovich “was acting on instructions from the American side to collect information about the activities of one of the enterprises of the Russian military-industrial complex that constitutes a state secret.”

The Journal “vehemently denies the allegations from the FSB and seeks the immediate release of our trusted and dedicated reporter, Evan Gershkovich,” the newspaper said. “We stand in solidarity with Evan and his family.”

The arrest comes at a moment of tensions between the West and Moscow over its war in Ukraine and as the Kremlin intensifies a crackdown on opposition activists, independent journalists and civil society groups.

The sweeping campaign of repression is unprecedented since the Soviet era. Activists say it often means the very profession of journalism is criminalized, along with the activities of ordinary Russians who oppose the war.

This week, a Russian court convicted a father over social media posts critical of the war and sentenced him to two years in prison. His 13-year-old daughter was sent to an orphanage.

Gershkovich is the first American reporter to be arrested on espionage charges in Russia since September 1986, when Nicholas Daniloff, a Moscow correspondent for U.S. News and World Report, was arrested by the KGB. Daniloff was released without charge 20 days later in a swap for an employee of the Soviet Union’s United Nations mission who was arrested by the FBI, also on spying charges.

At a hearing Thursday, a Moscow court quickly ruled that Gershkovich would be kept behind bars pending the investigation.

While previous American detainees have been freed in prisoner swaps, a top Russian official said it was too early to talk about any such deal.

In Washington, the Biden administration said it had spoken with the Journal and Gershkovich’s family. White House press secretary Karine Jean-pierre condemned the arrest “in the strongest terms” and urged Americans to heed government warnings not to travel to Russia.