American journalist Evan Gershkovich was formally charged with spying in Russia on Friday, as per Russian news agencies.

"FSB investigators 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," Russian state-run agency TASS said citing a law enforcement source.

The arrest of Wall Street Journal correspondent Gershkovich prompted an outcry from media outlets and rights groups, as well as government officials in Washington.

Gershkovich's arrest is seen as a serious escalation of Moscow's crackdown on the media. His publication, one of the most prestigious in the United States, "vehemently denies the allegations" against its "trusted and dedicated reporter".

The case has been classified as secret, limiting the amount of information available. His arrest also comes as Moscow's relations with Washington has been severely downgraded because of the Ukraine offensive.

Washington has long accused Moscow of arbitrarily arresting Americans in order to secure the release of detained Russians.

U.S. President Joe Biden called for Gershkovich's release on Friday, and the White House termed the accusations against him as "ridiculous."

Russia on Thursday said it was "pointless" to try to pressurize Moscow over the case.