Rapid Action Battalion-9 have arrested a youth on Monday night from Beanibzar upazila in Sylhet for allegedly being member of banned militant outfit Ansar Al Islam.
The arrestee was identified as Ziaul Haque, 18, resident of Gajukata village in the upazila.
Evidence of extremist social media posts published using Ziaul's cell phone was found, said Officer-in-Charge of Beanibazar police station Hillol Ray.
In primary interrogation Ziaul confessed he was actively working for Ansar Al Islam, he said
Rab members arrested Ziaul from a restaurant in Charkhai market while attending a secret meeting and handed him over to Beanibazar police station, said the OC.