Guwahati/New Delhi, June 29 (IANS): The NIA on Monday said it has arrested a self-styled regional commander of Naga militant outfit NSCN-K who masterminded the June 4 ambush on an Indian Army convoy in Manipur.

According to the National Investigation Agency (NIA), Khumlo Abi Anal of the National Socialist Council of Nagaland-Khaplang (NSCN-K) was arrested from Chandel district of Manipur.

Eighteen army personnel were killed when a convoy of 6 Dogra Regiment was ambushed on June 4 by militants in Paraolong village in Chandel district bordering Myanmar.

A statement issued by the NIA said this was the first arrest in its investigation into the killing.

"The accused Khumlo Abi was initially arrested by Manipur Police on June 11. Today (Monday), the NIA arrested him and produced him in the court of the Special NIA judge in Imphal. The judge sent him to nine days NIA custody till July 7," said an NIA official.

The statement said investigation into the attack revealed that Khumlo Abi Anal alias Ambison was a "senior functionary of the outfit and he was extensively involved in the conspiracy to attack the army personnel".

The militant was in touch with the other attackers "before and after the attack" on June 4, it said.

The NSCN-K had ambushed the army convoy in association with Kanglei Yawol Kanna Lup (KYKL) and the Kangleipak Communist Party (KCP).

The NIA's Guwahati branch has re-registered a case over the incident in compliance with an order issued by the union home ministry, under various sections of the Indian Penal Code, Arms Act, Explosive Substances Act, and Unlawful Activities (Prevention) Act.