Russian investigators have formally charged Wall Street Journal reporter Evan Gershkovich with espionage, Russian state media reported Friday, adding he denied the accusations.

“The FSB investigation charged Gershkovich with espionage in the interests of his country. He categorically denied all accusations and stated that he was engaged in journalistic activities in Russia,” an agency representative said, according to state news agency TASS.

The representative declined to comment further, as the journalist’s case was marked “top secret,” according to TASS.

Gershkovich was detained by Russian authorities last week, who accused him of spying, signaling a significant ratcheting of both Moscow’s tensions with the United States and its campaign against foreign news media.

A Moscow court on April 18 will hear an appeal filed by Gershkovich’s lawyers against his arrest, Russian state media said citing the court. The correspondent is currently held in the notorious Leftereovo pre-detention center until May 29.

Gershkovich’s arrest marks the first time an American journalist has been detained on accusations by Moscow of spying since the Cold War.

The Wall Street Journal on Friday issued a new statement condemning Gershkovich’s detention in Russia. “We’ve seen media reports indicating Evan has been charged,” the statement read. “As we’ve said from the beginning, these charges are categorically false and unjustified and we continue to demand Evan’s immediate release.”

Gershkovich’s arrest has also been widely condemned by western officials and the Journal vehemently denied the espionage charge against Gershkovich, describing his arrest “a vicious affront to a free press” which “should spur outrage in all free people and governments throughout the world.”

On Wednesday, Secretary of State Antony Blinken said he urged Russian Foreign Minister Sergey Lavrov to release Gershkovich immediately.

“In my own mind, there’s no doubt that he’s being wrongfully detained by Russia, which is exactly what I said to Foreign Minister Lavrov when I spoke to him over the weekend,” Blinken said during a press conference in Brussels. “But I want to make sure that as always, because there is a formal process, that we go through it and we will, and I expect that to be to be completed soon.” (CNN)

•PHOTO:Evan Gershkovich's arrest marks the first time an American journalist has been detained on accusations by Moscow of spying since the Cold War.