A Moscow court has extended the detention of Wall Street Journal reporter Evan Gershkovich, who was arrested on espionage charges at the end of March. During a brief hearing on Tuesday, the court ordered that Gershkovich should remain in jail until 30 August, Russian news agencies reported. His pre-trial detention had initially been scheduled to expire next week. He is being held in the notorious Lefortovo prison in Moscow, and could face a sentence of up to 20 years if found guilty. The case is still in the stage of investigation, with no date set for a trial. Tuesday’s hearing was closed to the public. Gershkovich, 31, is the first American journalist to be detained in Russia on spying charges since the end of the cold war. He was detained in the Urals city of Ekaterinburg while on a reporting trip at the end of March. Russia’s FSB security service has claimed he was collecting state secrets about the country’s military-industrial complex. Gershkovich and the Wall Street Journal have denied the charges, and the US state department has designated Gershkovich as “wrongfully detained”. An open letter to Russia’s foreign minister, Sergei Lavrov, signed by more than 300 foreign correspondents who previously worked in Russia, said: “We have no doubt that the only purpose and intention of his work was to inform his readers about the current reality in Russia.” Last month the US president, Joe Biden, praised the “absolute courage” of Gershkovich and said he was “working like hell” to secure his release. It has been widely speculated that Russia arrested Gershkovich with the hope of trading him for Russian intelligence officers or other people of interest to Moscow arrested in western countries, but so far there appears to have been little progress in discussions over a possible exchange. Last month, media were briefly allowed into court before a hearing in which Gershkovich appeared standing in a glass enclosure typical of Russian courtrooms. Marks, apparently from handcuffs, were visible on his wrists. His parents, Ella Milman and Mikhail Gershkovich, who fled the Soviet Union in the late 1970s and settled in the US, were reportedly in Moscow on Tuesday for the court hearing. “I want to say that I am not losing hope,” Gershkovich wrote in a letter to his parents from jail last month. “I read. I exercise. And I am trying to write.”