“The Service has uncovered the heinous role played by members of the Indigenous Peoples of Biafra (IPOB), in the abduction/kidnap of five Hausa-Fulani residents…The abducted men were later discovered at the Umuanyi forest, Abia State, where they were suspected to have been killed by their abductors and buried in shallow graves, amidst 50 other shallow graves of unidentified persons," Tony Opuiyo, the agency spokesperson for Nigeria's domestic spy agency, said in the statement later Saturday.
"Arrests and investigation conducted so far revealed that elements within the IPOB carried out this dastardly action," he added.
The agency said IPOB carried out the massacre of people of northern Nigerian origin at the time as part of its efforts to destabilize the country.
The IPOB movement was founded by Nnamdi Kanu, who is currently on trial on charges of treason and felony in a high-profile case in the country’s capital of Abuja.
Kanu’s unilateral declaration of independence from Nigeria as a separate Biafran state led to an ethnic conflict from 1967 to 1970, leaving about one million people dead, many of them from starvation and disease, as Nigerian troops blockaded the fledgling Republic of Biafra.
He was arrested in October 2015 for allegedly delivering "seditious messages" against the Nigerian government.
Kanu is accused by the state of "propagating a secessionist agenda" with the intention to "levy war against Nigeria;" a charge he has dismissed.
IPOB supporters, describing the allegations as baseless, have staged a series of protests across the country in recent months to demand his release and call for a breakaway state for the Igbo people, one of the largest ethnic groups in Africa.