The two Syrian nationals allegedly were members of the Nusra Front terrorist group.
The federal prosecutor's office said in a statement on Thursday that one of the detained, 35-year-old Abdalfatah H.A., allegedly committed war crimes by killing 36 employees of the Syrian government together with his Nusra Front unit in March 2013.
"Abdulfatah H. A. is suspected of having joined Jabhat al Nusra in 2013 and … of having killed 36 people protected by the humanitarian law during the regional conflict," the statement said.
A total of 36 people allegedly killed by Abdulfatah H. A. were soldiers of the Syrian army. These actions may be treated as war crimes.
Syria has been engulfed in a civil war for about six years with government forces headed by President Bashar Assad fighting a number of opposition groups and terror organizations such as Jabhat Fatah al Sham and the Islamic State, outlawed in Russia.