The warning said the attack targeted government buildings, worship centres, schools, and large crowds.
The Federal Government has been told to release Nnamdi Kanu following security alerts issued by US and UK.
US and UK had urged its citizens to leave Abuja over reports of looming terrorist attack.
Reacting, the Indigenous People of Biafra, IPOB, on Friday, urged the Department of State Services, DSS, to adhere to court orders and release its leader, Nnamdi Kanu.
IPOB called on DSS to release Kanu because the Federal Capital Territory, FCT, is about to fall to sponsored terrorists.
The group was reacting to the terror alert issued by the United States, United Kingdom, Canadian, and Australian embassies, on the possibility of a terrorist attack in Abuja.
The warning said the attack targeted government buildings, worship centres, schools, and large crowds.
Amid the terror alert, Kanu is locked up at the DSS facility in Abuja despite a court ruling ordering his release.
However, the spokesman of IPOB, Emma Powerful, in a statement, said: “The attention of the global family and movement of the Indigenous People of Biafra (IPOB) ably led by the great leader Mazi Nnamdi KANU has been drawn to the possible fall of Abuja to the Nigerian state-sponsored terrorists in the coming days.
“The US and UK security intelligence reports concerning the fall of Abuja and Nigeria to the terrorists are real, but Nigeria compromised security agencies, particularly their Military and DSS, are busy chasing armless and peaceful citizens of Biafra in Biafraland.
“The ability and preparedness of the Nigeria security forces, especially the Military (Army, Navy & Airforce) to defend the territorial borders of Nigerian has been greatly sabotaged and deteriorated to a level that will allow any foreign invader to walk into Nigeria’s capital with little or no resistance from the military.
“The Nigerian State has carefully positioned these terrorists to overrun Abuja once they feel that power will slip out of their hands during the upcoming charade they call an election, and they will, on behalf of the Fulani take over the reins of power in an invasion commando style as it happened in Afghanistan.
We are very much aware that the Fulani-controlled Federal Government of Nigeria has concluded every arrangement to hand over the Government of Nigeria to their sponsored terrorists in the coming days.
“IPOB and Mazi Nnamdi Kanu has been in the know of this sinister plan and have been hammering on it, but some so-called Biafran elites and other ethnic groups have refused to listen and heed the clarion call by IPOB, and its leader Mazi Nnamdi KANU to divide Nigeria to save all of us from this ugly situation.
“American and British governments have shut down their Embassies and have started evacuating their citizens in Abuja and its environs. If you’re still in Abuja and still thinking this warning is a joke, you will have yourself to blame.
“IPOB state unequivocally that the Nigeria Government and Malami must adhere to and implement the ruling of the Court of Appeal, which declared Kanu a free man discharged and acquitted of all spurious allegations and charges.
“We are warning the Fulani Government to release Mazi Nnamdi Kanu urgently.”