Russia's Federal Security Service (FSB) says a Russian woman has been detained on suspicion of state treason for allegedly spying for Ukraine in the Russian-occupied Crimean Peninsula.

Russian news agencies quoted the FSB as saying on November 29 that the Russian national was being accused of attempting to obtain Russian military secrets "on instructions from the Intelligence Directorate of Ukraine's Ministry of Defense."

She was detained in the city of Sevastopol.

The woman has been recruited by Ukraine’s intelligence services, the FSB said, but didn't provide further details.

Sevastopol’s Lenin district court has opened a criminal case, Interfax reported, citing a court official. The woman faces up to 20 years in prison if found guilty of state treason, it added.

Russia illegally annexed the Crimean Peninsula from Ukraine in 2014.

Based on reporting by Interfax and Reuters