MEND had earlier alleged that Kanu secretly reached a deal with the Federal Government for his release.
The group said it will not enter into any form of dialogue with the government if Kanu is not released.
IPOB also expressed confidence that their leader, who is currently standing trial for treason, will not abandon the Biafra struggle.
It also added that the continuous detention of Kanu is a slap on the rule of law and judicial process.
The group said “For Buhari to continue to keep Kanu in custody after a court of competent jurisdiction had granted him (Kanu) bail is enough corruption.
“They don’t know this man called Nnamdi Kanu. They can’t intimidate Kanu by dumping him in prison. He can’t beg anybody for his freedom.”
Accoding to IPOB spokesman, Emma Powerful, “Instead of our leader to renounce Biafra, he would renounce Nigeria publicly, mark our words.
“We are not after securing bail for our leader; we are after his freedom and freedom for the people of Biafra.
“Even a child born today knows that any attempt to tamper with Nnamdi Kanu’s life will bring about catastrophic consequences.
“Should anything happen to Kanu, Somalia will be a paradise, compared to what will happen in Nigeria.
“We are not asking for anything short of his immediate and unconditional release, as ordered by an Abuja Federal High Court.”
The Igbo socio-cultural group, Ohaneze Ndi-Igbo also called on President Buhari to resume negotiations with the IPOB leader, Kanu.