Naga insurgent group NSCN-IM on Wednesday held a meeting with a government representative in an effort to find a permanent solution to the decades-old vexed problem, officials said.
The NSCN-IM delegation, led by senior leader V S Atem, met interlocutor A K Mishra at an undisclosed location in the national capital.
The participants discussed the rebel group's core demands, including a separate flag for the Nagas.
The dialogue remained inconclusive and is likely to resume on Thursday, an official privy to the talks said.
The NSCN-IM delegation also requested the interlocutor to arrange a meeting with Prime Minister Narendra Modi.
Top leader of the group, Thuingaleng Muivah, did not take part in this round of the meeting.
On Tuesday, in its mouthpiece Nagalim Voice, the NSCN-IM said it stands by its demand for unification of Naga-inhabited areas for the Nagas and a separate flag and these are "non-negotiable".
The NSCN-IM also said it is "ironic" to point out that the prime minister "who loves to advertise" his achievements is expected to take the Naga issue to its logical conclusion as the stalled "Indo-Naga talks" pick up the threads with focus on framework agreement and formulated papers.
The framework agreement was signed on August 3, 2015 in presence of the prime minister to hammer out a permanent solution to the Naga issue.
The group said "Modi cannot simply shy away" from Naga issue but have a relook through the prism of framework agreement which is his "own political brainchild".
"The credit he has taken in bringing about FA (framework agreement) should be unerringly interpreted to take forward in solving Naga issue," the editorial said.
It said the stand of the NSCN-IM on framework agreement has been distinctly stated time and again and the decision of the (Naga) "National Assembly" on May 31 and the solemn declaration (resolution) adopted on August 26 by the Naga National Workers of NSCN from Nagaland state reaffirming "one people one nation" and to stand by the Framework Agreement, is on record.
"The unifying principle of One People One Nation symbolised by the God given Naga Nation Flag is non-negotiable in the name of Naga political solution," it said.
Nagaland's neighbouring states - Manipur, Assam and Arunachal Pradesh - have been vehemently opposed to the idea of unification of Naga inhabited areas under their jurisdictions.
The framework agreement came after over 80 rounds of negotiations spanning 18 years, with the first breakthrough made in 1997 when the ceasefire agreement was sealed after decades of insurgency in Nagaland which started soon after India's independence in 1947.
However, the talks with the NSCN-IM was going nowhere as the group has been insisting for a separate Naga flag and constitution, a demand rejected by the central government.
Separately, the government is also holding peace parleys with splinter groups of the NSCN after entering into ceasefire agreements.
The groups which have entered into ceasefire agreements are: NSCN-NK, NSCN-R, NSCN K-Khango and NSCN-K Niki.