As many as 10 NDFB-Songbijit militants were killed in the last five months in operations against the insurgent outfit in Assam, Director General of Police Khagen Sarma said on Tuesday.

"After the December 23 last violence, the police, Army and paramilitary forces launched a combined operation against the NDFB-S. Ten militants were killed in encounters with the security forces," Sarma told reporters here.

"A total of 343 NDFB-S cadres, including 204 active ones, were arrested; over 100 factory-made sophisticated arms, 164 grenades and 62.5 kg explosives were recovered during the operation so far," he said.

Stating that the security forces had destroyed a tactical camp of the militant group at Ultapani in Kokrajhar district on May 8, the DGP said police had reports that till that morning 35 to 40 cadres, including NDFB-S top leaders ‘Deputy Army Chief’ G Bidai and ‘Commandent’ Batha Mushahary, were in the camp.

The cadres had mostly fled towards Manas National Park in lower Assam and other places of the state and "we are after them," the DGP said.

While Bidai alias Bishnu Goyari was in Assam, the underground group’s central committee members were in hiding in Myanmar, Sarma said.

Bidai, carries a cash reward of Rs 5 lakh on his head, and had executed the plan for the December 23 attacks killing nearly 100 Adivasis in lower Assam.

On the security forces strength in counter-insurgency operations, he said, "50 additional companies were sent by the Centre for the operations following the December 23 violence. The Army also increased its forces."

To a query on how extremists procured factory-made original arms, the DGP said, "They have a big market in different areas. They come mainly from Myanmar, through the land border corridors of Bangladesh, Mizoram and Nagaland. We also see that small weapons like pistols and revolvers come from Bihar to Dimapur in Nagaland."

On Bangladesh’s Jamaat-ul-Mujahideen’s presence in Assam, the top cop said, "JMB’s base is not much in the state. We are continuously breaking them."