Former ballerina detained in Russia has appeal denied in Siberian court

LONDON -- A court in Siberia denied on Thursday the appeal of Ksenia Karelina, a dual American-Russian citizen, who appeared via video link to appeal her detention on charges of treason.

Karelina, 33, was arrested on Jan. 27, according to Russian state media. The Sverdlovsk Regional Court on Thursday extended her pre-trial detention in a jail in Yekaterinburg, Russia, until April 6.

A former ballerina who lives in California, Karelina holds both U.S. and Russian citizenship. She was jailed for allegedly organizing fundraisers for Ukraine's military, attending pro-Ukraine rallies, and posting messages against Russia's war in Ukraine, according to Russian state media.

A U.S. official said diplomats at the U.S. Embassy in Moscow were working to learn more and gain access to Karelina.

White House National Security Communications Adviser John Kirby last week urged U.S. passport holders to "depart immediately" from Russia.

"So if you’re a U.S. citizen, including a dual national, residing in or traveling in Russia, you ought to leave right now if you can," Kirby said following the arrest.

ABC News' Joe Simonetti, Molly Nagle and Shannon K. Crawford contributed to this report.