A suspected Kamtapur Liberation Organisation (KLO) militant was arrested in Siliguri on Friday morning, police said.
The man was arrested from Khalpara area of the city by the North Bengal Special Task Force of police, they said.
The arrested, a resident of Srirampur Assam's Kokrajhar, was part of a KLO group that has been operating in Siliguri, they added.
He was living here as a labourer for the last six months, Deputy Commissioner of Police Sudip Bhattacharya said.
A hunt is on for other members of the group operating in Siliguri, he said.
When produced at court, he was sent to 14 days in judicial custody.
KLO, declared a terrorist group by the Centre, came into existence in 1995 after members of the Koch-Rajbongshi community of the All Kamtapur Students Union (AKSU) organised an armed struggle for liberation, demanding a separate Kamtapur nation, carved out of India and Nepal.
(With Inputs from ANI)