In a major boost for the government and the state security forces, 20 top leaders of the tribal militant outfit All Adivasi National Liberation Army, including its chief Biren Gond alias Sanjay Lakra, have surrendered in Assam.

Lakra, along with his comrades, surrendered at Bokajan in Karbi Anglong hill district of Assam on Sunday. The surrender of the top leaders of the outfit came after the recent arrest of its previous commander John Toppo in Nagaland and founder leader Nirmal Tirkey in Jharkhand.

The militants also handed over eight 9 mm pistols, one carbine, 66 detonators, two timer devices, five improvised explosive devices and several rounds of live ammunition.

An army source informed that with the surrender of its top leaders, the AANLA has only 80-odd cadres left in its outfit. The AANLA was floated in 2003 and is mainly active in Karbi Anglong and Golaghat districts of Assam.

The proscribed Kuki Revolutionary Army and Naga rebel group NSCN-IM had helped the AANLA in emerging as the militant face of Adivasi tribes in Assam, which are fighting for their inclusion in the Scheduled Tribe category.

The outfit had triggered a blast on the Dibrugarh-New Delhi [Images] Rajdhani Express at Chongajan on December 13, 2007 that claimed four lives.

It has also been involved in extortion activities in the tea belts of Golaghat, Jorhat, Sivasagar and Karbi Anglong districts of the state.

It also had close coordination with the banned United Liberation Front of Asom. The outfit has expanded its influence to tribal-dominated areas in Udalguri, Kokrajhar and Sivasagar districts.

An army source informed that the AANLA was under tremendous pressure from the security forces since the arrest of four senior leaders of the outfit at Bokajan on December 26.