MOSCOW (AP) — Lawyers for an American reporter for The Wall Street Journal arrested in Russia on espionage charges have appealed his arrest, a court in Moscow announced Monday.

Evan Gershkovich, 31, was detained last week in Yekaterinburg, Russia’s fourth-largest city. It was the first time a U.S. correspondent had been detained on spying accusations since the Cold War. The Journal has said it “vehemently denies” the charges and demanded his release.

At a hearing Thursday, Moscow's Lefortovsky District court quickly ruled that Gershkovich would be kept behind bars for two months pending the investigation.

On Monday, the court reported that it has received an appeal against Gershkovich’s arrest filed by his defense, according to Russian news agencies. No date for the appeals hearing has been set yet.

Gershkovich was put in Moscow's Lefortovo prison, which dates from the czarist era and has been a terrifying symbol of repression since Soviet times.

Russia’s Federal Security Service, the top successor to the Soviet-era KGB that is known by the acronym FSB, accused Gershkovich of trying to obtain classified information about a Russian arms factory. The Kremlin alleged that Gershkovich was caught red-handed, without offering details.

President Joe Biden on Friday urged Russia to release Gershkovich. “Let him go,” Biden told reporters at the White House when asked if he had a message for Russia.

Secretary of State Antony Blinken urged his Russian counterpart Sunday in a rare phone call between the diplomats since the start of the Ukraine war, to immediately release Gershkovich as well as another imprisoned American, Paul Whelan.