Kanu's lawyer says he has been illegally detained since the secret police arrested him on Oct. 17.
Two other courts had ordered Kanu's unconditional release but the government refused, escalating charges against him to terrorism.
Also Friday, Dutch lawyer Goran Sluiter asked the International Criminal Court in The Hague to investigate President Muhammadu Buhari, charging he bears criminal responsibility for crimes against Biafran separatist protesters including murder, torture, enforced disappearance and arbitrary arrest and detention.
Sluiter says violence against Biafrans in Nigeria has intensified since Buhari's election last year.
Igbo people from southeastern Nigeria fought a civil war to form an independent Biafra in the 1960s that killed 1 million people..