Russian prosecutors have charged Wall Street Journal reporter Gershkovich with espionage -- the first time such a criminal accusation has been levelled against a Western reporter in Russia since the fall of the Soviet Union.
Gershkovich, his employers and the White House all reject the charges, which carry a maximum sentence of 20 years.
"Gershkovich will remain in custody until March 30, 2024," the Moscow courts service said in a statement following a hearing at the Moscow City Court.
The appeal was a technical challenge against an earlier decision to extend Gershkovich's pre-trial detention. It did not concern the substance of the case.
His shock arrest by FSB counterintelligence agents in the Urals city of Yekaterinburg last March while on a reporting trip triggered uproar in Washington.
And the United States has slammed the Kremlin over his ongoing detention, which will hit the one-year mark on March 29.
"The charges against Evan are baseless. The Russian government has locked Evan up simply for reporting news," US Ambassador to Russia Lynne Tracy, who attended the hearing, said outside the court Tuesday.
President Vladimir Putin said earlier this month he would like to see Gershkovich released as part of a prisoner exchange.
In remarks to conservative American TV commentator Tucker Carlson, he said talks between Russia and the United States about a possible swap were ongoing.
The Russian leader made clear he wanted any deal to involve the release of a Russian jailed in Germany for killing a Chechen dissident.
Russia separately on Tuesday banned US-funded Radio Free Europe/ Radio Liberty (RFE/RL), putting its staff and contributors at risk of prosecution.
The outlet's name was listed on the Ministry of Justice database as an "undesirable organisation".
In Washington, State Department spokesman Matthew Miller said the move curbed freedom of speech.
"It is quite clear that they do not want their people to have information about what the Russian regime does abroad, what the Russian regime does to its own people," Miller told reporters.
That same day, the supreme court of Russia's Tatarstan region rejected an appeal by a jailed RFE/RL editor, US-Russian journalist Alsu Kurmasheva, to be transferred from pre-trial detention to house arrest, her employers reported.
Kurmasheva, who lives in Prague, had her passports confiscated and was arrested in October while back in Russia for a family emergency.
She faces charges of failing to register as a "foreign agent" and contravening Russia's strict military censorship laws, her employers say.
RFE/RL said the court ordered Kurmasheva to be held in jail until at least April 4, rejecting the appeal, which had been lodged on health grounds.
Washington has accused Moscow of arresting American citizens on baseless charges to use them as "bargaining chips" to secure the release of Russians convicted abroad.
Former US marine Paul Whelan, in prison in Russia since 2018 and serving a 16-year sentence on espionage charges, is also pushing to be included in any future prisoner exchange.
"The United States will not rest until Evan and Paul are free and back home in the United States with their families," Tracy said.
Separately on Tuesday, Russia's FSB security service said it had arrested a 33-year-old dual US-Russian citizen in Yekaterinburg -- the same city where Gershkovich was arrested -- on suspicion of treason.
It said the woman, a Los Angeles resident, had been helping Ukrainian organisations collect funds "to purchase tactical medical items, equipment, means of destruction and ammunition for the Ukrainian armed forces".
The FSB said she had been acting "against the security of our country" and had been supporting the Ukrainian army while in the United States.
The United States said it was seeking consular access but declined further comment, citing privacy laws.
Treason is punishable by up to life in prison under legislation toughened since the start of Russia's military offensive against Ukraine.
