Moscow student Varvara Karaulova, 19, will remain in custody until March 27 after a Moscow City Court rejected her lawyer's appeal, the RIA Novosti news agency reported Tuesday.
A panel of judges at the Moscow City Court ruled against her lawyer's appeal that the teenager's level of restraint be changed or that she be transferred to house arrest.
The Moscow State University student had taken an interest in Arabic culture and Islam. Following her disappearance in May 2015, her parents discovered that she had an online relationship with a recruiter for the Islamic State.
Karaulova was detained on the Turkish-Syrian border in October 2015 and brought back to Moscow. Although the Investigative Committee originally said that there was no plan to open a criminal case against her, she was later arrested and put in pretrial detention on suspicion of attempting to join the Islamic State and recruiting Russians to join the militant group.
Karaulova faces up to 10 years in prison if convicted.
Islamic State is a terrorist organization banned in Russia.