Russia detained American journalist Evan Gershkovich for alleged espionage while he was on a reporting trip, the first time a U.S. reporter has been held on spying charges since the Cold War.

The 31-year-old Wall Street Journal reporter was arrested in Yekaterinburg, about 1,400 kilometers east of Moscow, by Federal Security Service agents and brought to Moscow, where a district court ordered him to be held until at least May 29. The case was classified as "top secret.”

The newspaper denied the allegations and asked for the immediate release of "our trusted and dedicated reporter.” A State Department spokesman said the U.S. had asked for consular access and it would be several days before the request is granted.