A tribal Naga rebel group attacked militants belonging to the outlawed United Liberation Front of Asom (ULFA) in Nagaland, killing two and abducting seven members of the outfit, according to an ULFA statement in Guwahati on Monday.
Police say the incident could snowball into a major conflict between the two groups.
The statement said heavily armed militants of the National Socialist Council of Nagaland (NSCN), which is led by guerrilla leaders Isak Chishi Swu and Thuingaleng Muivah, attacked ULFA rebels near village Tizit in Nagaland's Mon district late on Sunday.
"Tangkhul Naga's of the NSCN-IM attacked and killed two of our cadres and kidnapped seven more while our boys were passing through that area," Raju Baruah, chief military spokesperson of the ULFA, said in statement.
The ULFA is an influential separatist group in Assam fighting for an independent homeland since 1979. It has bases in Myanmar and has to traverse through parts of Nagaland to reach their camps on the other side of the border.
"We urge the NSCN-IM to hand over the seven abducted ULFA cadres within three days. We have never disturbed the movement of Nagas through Assam and this incident is quite serious," the ULFA statement said.
There was no immediate comment from the NSCN-IM.
The ULFA in the past were imparted military training by the NSCN-IM although the Assamese rebel group has now severed links with it.
The ULFA is aligned to the rival NSCN group led by factional leader SS Khaplang.
The two NSCN factions are fighting a bitter turf war in Nagaland for territorial supremacy. "The attack on the ULFA by the NSCN-IM is probably due to the differences we have and could be because the ULFA is staying in Myanmar under our patronage," a top NSCN-K leader said.