The United States has designated journalist Evan Gershkovich as being “wrongfully detained” by Russia and called for his immediate release.
Mr Gershkovich, an experienced Russia reporter, was arrested last month in the city of Yekaterinburg while working for the Wall Street Journal (WSJ).
He has since been formally charged with spying, but the WSJ denies this.
It is the first time Moscow has accused a US journalist of espionage since the Soviet era.
The “wrongfully detained” designation in the US means the case will now be transferred to the office of the Special Envoy for Hostage Affairs. This will raise the profile of the case and allow the government to allocate more resources to securing his release.
US Secretary of State Antony Blinken “made a determination that Evan Gershkovich is wrongfully detained by Russia”, state department spokesman Vedant Patel said.
He called for the “immediate release” of Mr Gershkovich and condemned “the Kremlin’s continued repression of independent voices in Russia, and its ongoing war against the truth.”
The WSJ said: “The distinction will unlock additional resources and attention at the highest levels of the US government in securing his release.”
“We are doing everything in our power to support Evan and his family,” it added.
Russia has not granted US consular officials access to Mr Gershkovich, which is in violation of international law, Mr Patel told reporters earlier on Monday.
Last week the Russian foreign ministry said the issue of consular access was being resolved but added that the “fuss in the US about this case, which was aimed at pressurising the Russian authorities… was hopeless and senseless”.
Mr Gershkovich, 31, is well known among foreign correspondents in Moscow. BBC Russia Editor Steve Rosenberg describes him as an excellent reporter and a highly principled journalist.
The WSJ said its reporter had dropped out of contact with his editors on 28 March while in Yekaterinberg.
Russia’s FSB security service said it had halted “illegal activities” by detaining the journalist.
Press freedom watchdog Reporters Without Borders said he had gone to Yekaterinburg to cover Russian mercenary group Wagner, which has taken part in some of the heaviest fighting in eastern Ukraine.
According to a report by the James Foley Legacy Foundation, which advocates for the freedom of Americans being held hostage abroad, at least 65 Americans were being unfairly detained abroad in 2022.
The foundation is named after a US journalist abducted in Syria and killed by the Islamic State group in 2014.