"The Registrar General of India, by rejecting the longstanding demands of these communities, has proved that the Indian Constitution does not intend to safeguard the interests of indigenous people - only endanger their future," said pro-talks Ulfa chief Rajkhowa.
Granting of tribal status to these communities was seen as an important way of ensuring that the political rights of indigenous people are safeguarded in the face of the rising illegal Bangladeshi immigrant population.
Ahoms and Muttocks form the backbone of the Ulfa leadership and its cadres. The plan to grant them tribal status with easier access to jobs and other modes of employment was also seen as a means to wean away youths from the Ulfa's influence.
A top official admitted that this development could pose problems.
"There is no doubt about its implications on the talks, but nothing is final as of now. So we still hope to find a way out. Moreover, the opinion of other government entities would have a final bearing on the matter," the official said.
While Rajkhowa is an Ahom, anti-talks leader Paresh Barua hails from the Muttock community. The subsequent round of talks with the Rajkhowa faction is expected to take place in January.