Perviy Otdel, a legal rights group, told The New York Times that Karelina is accused of sending just over US$50 to Razom for Ukraine, a New York-based non-profit human rights organisation.
She is also accused of repeatedly participating in public events in support of Ukraine in the US.
The FSB said Karelina, had been acting “against the security of our country”, news agencies reported.
Russian-born Karelina, who lives in Los Angeles, obtained US citizenship in 2021.
She was detained on a trip back to Russia to see her parents. Analysis of her social media profiles suggest she attended the Ural Federal University in Yekaterinburg.
According to Perviy Otdel, a group of Russian lawyers who specialise in politically charged cases, the number of treason cases in the country has been rising steadily since the invasion of Ukraine.
A video shared by Russian state news agency Tass shows the woman being handcuffed while wearing a cream puffer jacket with a white hat pulled down over her eyes. She is escorted by a man in military camouflage who appears to be a Russian soldier.
She is ushered into a car and later appears behind bars in what appears to be a courtroom.
In a later image, the woman’s hat is removed, showing her brown hair with blonde highlights tied up in a bun.
Meanwhile, Moscow City Court has rejected an appeal against detention filed by Gershkovich’s lawyers.
The journalist, who is accused of espionage after being arrested while reporting in Yekaterinburg, will spend at least a year in custody before coming to trial.
Earlier this month in an interview with Tucker Carlson, a US political commentator, Putin hinted that Russia would be willing to release Gershkovich in exchange for Vadim Krasikov, a Russian hitman detained in Germany for the murder of a Chechen fighter in Berlin in 2019.
