South Korean officials say a teenager who went missing in Turkey last month is probably the first known South Korean to join the Islamic State group.

Opposition lawmaker Kim Kwang Jin said Tuesday that the director of South Korea's National Intelligence Service, Lee Byung-kee, told legislators in a closed-door meeting that the 18-year-old man is alive in Syria and with an Islamic State group unit that trains combat personnel.

Kim said Lee didn't reveal how the spy agency obtained the information or where the Islamic State group unit is based.

The man was last seen leaving a hotel in the Turkish border town of Kilis on Jan. 10. Seoul's Foreign Ministry confirmed that he would be the first known South Korean to join the militant group.