The ultras were arrested by personnel of the Assam Rifles on Monday while they were trying to sneak into Myanmar via Mon district, defence sources said on Tuesday.
Five of the arrested belonged to the outfit's dreaded 28th battalion which recently carried out the killing of non-Assamese migrant labourers in upper Assam. The two women cadre were handed over to the police.
Equipments, including radio sets, dicta phones, SIM cards, radio transistor and knives were recovered from them, they said.
The Assam Rifles said the drive against ULFA militants would continue in Nagaland in the coming days even though the ceasefire was in force in the state.
They asked NSCN and villagers not to collude and provide shelter to the militants from Assam who frequently adopt hit-and-run tactics and seek safe refuge either in bordering districts of Nagaland or Arunachal Pradesh.