Dristhi Rajkhowa's aide Peramisom Marak had a .9 mm pistol and several rounds of ammo on him.
A Bangladeshi national said to be a close associate of Drishti Rajkhowa, a United Liberation Front of Asom (ULFA) leader, was arrested today from western Meghalaya, an official said.
Peramisom Marak was arrested from Kachhuadogri area in Meghalaya's West Garo Hills district bordering Bangladesh, Border Security Force (BSF) spokesman Sushil Kumar Singh said.
The troopers also seized one .9 mm pistol, two .9 mm magazines and eight rounds of ammunition of the same calibre and a mobile phone with a Bangladeshi SIM card from him.
"Marak told interrogators that he has been working with ULFA in Bangladesh for three years and maintains close association with Rajkhowa, the deputy chief of ULFA's military wing and his bodyguards," Mr Singh said.
The BSF official said Marak also confessed to smuggling arms and ammunition from Bangladesh through the Garo Hills, besides assisting ULFA cadres in Bangladesh's Badagazni village to criss-cross the India-Bangladesh border with the help of some Indian accomplices.
Mr Singh said Mr Marak is also wanted by the Bangladesh government for his illegal activities.
Meghalaya shares a 443-km border with Bangladesh, part of which is porous, hilly, unfenced and thus prone to frequent infiltration.
"We are trying to find the Indians providing assistance to the ULFA rebels in bordering areas," Mr Singh said.
The troopers have since handed over Mr Marak to the Meghalaya Police for further action.