The Russian state news agency TASS has reported: "The Lefortovo court arrested journalist Evan Gershkovich in a case of espionage, law enforcement officials told us. He was chosen as a measure of restraint in the form of detention, the source of our agency said."

The Federal Security Service of Russia arrested Evan Gershkovich, a journalist from the Wall Street Journal, on allegations of spying.

The Federal Security Service, known as FSB, said in a statement it detained Gershkovich, a US citizen, in the eastern city of Yekaterinburg, about 900 miles east of Moscow in the Ural Mountains.

FSB said the reporter was "on the instructions of the United States, he was collecting information about one of the enterprises of the Russian military-industrial complex, which constitutes a state secret."

WSJ released this statement about Gershkovich's arrest: 

"The Wall Street Journal vehemently denies the allegations from the FSB, and seeks the immediate release of our trusted and unbiased reporter, Evan Gershkovich." 

Gershkovich has worked for WSJ in Moscow for more than a year. He previously worked in Russia for Agence France-Presse and The Moscow Times. 

Over the past year, the reporter has authored articles about the effects of Western sanctions on Russia's economy and the faltering relations between Moscow's elite and the Wagner paramilitary group.

The FSB said it had "stopped the illegal activities" that Gershkovich was conducting and opened an espionage case against him in Yekaterinburg.