Russian authorities have arrested a reporter for the Wall Street Journal on espionage charges.

The Federal Security Service (FSB), the top KGB successor agency, said on Thursday that Evan Gershkovich, a US national, was detained in the Ural Mountains city of Yekaterinburg, suspected of trying to obtain classified information.

It alleged that Gershkovich “was collecting classified information about the activities of one of the enterprises of the Russian military-industrial complex that constitutes a state secret”.

Hours later, Gershkovich was formally arrested at a Moscow court pending trial. He will be held in pre-trial detention until May 29.

Gershkovich, a Russian speaker who was properly accredited as a journalist, was covering the war in Ukraine, elopments in Russia, and the Wagner mercenary group from the WSJ’s Moscow bureau.

The FSB did not say when the detention took place.

Gershkovich could face up to 20 years in prison if convicted of espionage.

“The Wall Street Journal vehemently denies the allegations from the FSB, and seeks the immediate release of our trusted and unbiased reporter, Evan Gershkovich,” the paper said in a statement.

He is the first reporter for a US news outlet to be arrested on spying charges in Russia since the Cold War.

Al Jazeera’s Dorsa Jabbari, reporting from Moscow, said Gershkovich had lived in Russia for the past six years.