A Russian judge denied the appeal of Evan Gershkovich, a Wall Street Journal reporter who has been charged with spying, in a Moscow court on Tuesday.
The reporter, a correspondent with the paper's Moscow bureau, stands accused of “acting on the instructions of the American side” and collecting state secrets about the military.
A Moscow City Court heard an appeal from Tatyana Nozhkina and Maria Korchagina of the ZKS law firm, who are representing Gershkovich.
"Of course he didn’t agree with his detention," Korchagina told ABC News outside the courthouse on Tuesday. "And he would like to prove that he is not guilty. And he would like to prove that there is a place for freedom of journalism."
Gershkovich, who was wearing a checkered shirt and jeans, arrived at about noon local time. He stood inside a glass detention area within the courtroom, a standard practice for criminal defendants in the Russian court system. Members of the press were escorted out of the courtroom and into a nearby viewing area before the hearing began.
Lynne Tracy, the U.S. ambassador to Russia, was present in the courtroom. Speaking outside the court following the denial, Tracy said the charges were "baseless" and called again for Russian authorities to release Gershkovich.
"I can only say how troubling it was to see Evan, an innocent journalist, held in these circumstances," Tracy said.
MORE: 'He was quite cheerful': Russian monitor visits detained Wall Street Journal reporter in Moscow jail for first timeWith his request for bail or house arrest denied, Gershkovich is expected to be held in prison until at least May 29, the scheduled end of his initial detention. His pre-trial detention may also be extended beyond that date.
Russia's FSB intelligence agency said on March 30 that it had detained the WSJ journalist for spying.
"He was arrested in Ekaterinburg during an attempt to receive secret information," Interfax, a Russian state-affiliated news agency, reported at the time, quoting FSB officials.
MORE: WSJ reporter detained in Russia on spying chargeThe Wall Street Journal said the same day that it "vehemently denies" the spying allegations brought by Russia's intelligence service against its reporter.
The paper "seeks the immediate release of our trusted and dedicated reporter," a WSJ spokesperson said in a statement, adding, "We stand in solidarity with Evan and his family."
"He is a distinguished journalist and his arrest is an attack on a free press and it should spur outrage in all free people and governments around the world," Emma Tucker, WSJ editor-in-chief, and Almar Latour, WSJ publisher and Dow Jones CEO, said in a joint statement.
Gershkovich has been held in Lefortovo prison as he awaits trial. Tuesday's hearing marked his first public appearance since his arrest.
U.S. officials on April 10 said they determined Gershkovich had being "wrongfully detained" by Russia, a designation that would allow the U.S. government to more aggressively advocate for his freedom.
Tracy, the U.S. ambassador, had visited the detained reporter on Monday, according to the State Department.
“I can report based on what Ambassador Tracy has said, he’s in good health and good spirits considering the circumstances," Secretary of State Antony Blinken told reporters. "We continue to call for his immediate release from this unjust detention."
Speaking outside the court on Tuesday, Tracy called for the release of both Gershkovich and Paul Whelan, another American detained in Russia.
"We also call for the immediate release of Paul Whelan," Tracy said. "Paul has been held for more than four years in Russia. Both men deserve to go home to their families now."
ABC News' Patrick Reevell, Shannon K. Crawford, Teresa Mettela, Ellie Kaufman, Matt Seyler and Cindy Smith contributed to this report.