Separatist leader and Islamic Students League chairman Shakeel Ahmad Bakshi was arrested from his office in Batamaloo locality in Srinagar.
"We have arrested him (Bakshi) from his office in Batamaloo," South Srinagar SP Sujit Kumar said.
Bakshi was arrested for a case registered against him in 2009 under the Unlawful Activities Act, he said.
Earlier this month, police arrested chairman of Jammu and Kashmir Muslim League Mushtaq ul Islam from his residence in the same locality.
Bakshi is the founder member of ISL which was associated with the united Hurriyat Conference in mid-1990s for a brief period.