"At 11:30pm on Sunday, the NDA blew up Nigerian National Petroleum Corporation (NNPC) gas pipeline at Nsit-Ibom," in Akwa Ibom state, the group said in a terse statement.
NNPC officials were not immediately available for comment, but the attack is bound to worsen gas supplies to power plants in a country reeling from daily outages.
The Avengers have claimed a string of devastating attacks against the NNPC as well as oil majors Shell, Chevron, Exxon and Eni since February.
The rebels want oil majors to leave the Niger delta, blaming them for contributing to widespread poverty and under-development of the region.
The group also wants self-determination for the oil-producing states in the delta region and political autonomy.
The Avengers have rejected a government truce to end violence.