MOSCOW, Nov. 29 (Xinhua) -- The Russian Federal Security Service has detained a woman suspected of collecting secret military information for Ukraine's defense ministry, it said in a statement on Friday.

The woman, a Russian citizen, was detained in Sevastopol, the largest city of Crimea.

The statement gives no further details about the detainee.

It said that a criminal case has been opened on the grounds of high treason and that an investigation is underway.

The autonomous republic of Crimea, formerly a part of Ukraine, was incorporated into Russia in March 2014 following a referendum not recognized by Ukraine.