The National Investigation Agency (NIA) on Sunday interrogated Devinder Singh Behl at his resident here, over his suspected connections with Separatist elements.
The NIA is also conducting raids at various premises of Behl, who was supposedly connected to Hurriyat before 2008.
Earlier on Wednesday, Separatist leader and Democratic Freedom Party (DFP) chairman Shabir Shah, was sent to a seven-day Enforcement Directorate (ED) custody in connection with a terror-funding case.
Shah was under house detention for a very long time, in Jammu and Kashmir's Srinagar. The reason for his arrest is yet unknown as he was already under house arrest since many months.
On July 24, the NIA arrested seven separatists over money laundering charges, for funding terror in the Kashmir Valley.
All seven separatist leaders - Altaf Shah, Ayaz Akbar, Peer Saifullah, Mehraj Kalwal, Shahid-ul-Islam, Naeem Khan and Bitta Karate - were later sent to 10-day NIA custody.
The accused have been charged under various sections of the Indian Penal Code (IPC) and the Unlawful Activities (Prevention) Act.
Six of them were arrested from Srinagar, while Bitta Karate was arrested from New Delhi.
The NIA visited Srinagar in May to probe the alleged funding by Pakistan for illegal activities in Kashmir and questioned several separatist leaders on the issue of raising, collecting and transferring funds via the Hawala route and other channels to fund terror activities in Kashmir.
The NIA sleuths specifically questioned separatist leaders Farooq Ahmed Dar alias Bitta Karate and Gazi Javed Baba at that time.
The NIA is said to be probing all aspects of funding to separatist leaders and how they reportedly used these funds to fuel unrest in the Kashmir Valley.