The group includes many women and children who were abducted in March from an area close to Cameroon.
In the memorandum, the organisation demanded immediate action against armed Kuki militants allegedly involved in the abduction of six Naga civilians.
More than 38 people were abducted and held hostage by armed groups in Kangpokpi and Senapati districts on May 13
Several abducted activists aboard the Global Sumud Flotilla have released pre-recorded messages calling for help.