Kanu is facing treason charges at the Federal High Court in Abuja.
More than 1 million people died in Nigeria's war with Biafra.
Kanu's defense wants to overturn a ruling that allows witnesses to testify anonymously.
The pro-Biafra activist will return to court for a bail hearing on May 5.
The pro-Biafra activist is on trial for treasonable felony and faces a maximum life sentence.
Nnamdi Kanu, the pro-Biafra leader, goes on trial for treasonable felony in Nigeria on Monday.
Uchechi Okwu-Kanu says she almost miscarried during her husband's detention.
Angela Rayner says that allegations of human rights abuses against pro-Biafra protesters in Nigeria require investigation.
A revived secessionist movement is adding to Nigeria's troubles.
Amnesty International says it is investigating alleged human rights abuses against pro-Biafran protesters.
The leader of the Indigenous People of Biafra goes on trial on Tuesday, charged with treason.
A maritime security analyst says negotiations are ongoing for the freeing of five captives.
Militants reportedly took control of a ship off Nigeria on Friday and are demanding Nnamdi Kanu's release.
After Boko Haram in the northeast, a number of threats are destabilizing Nigeria's south.
The militants have threatened to blow up the ship and its crew if the pro-Biafran leader is not released.
Human rights lawyers allege that the Nigerian president has committed crimes against humanity against pro-Biafran activists.
Thousands of Nigerians are demanding independence for a region in southeast Nigeria.
Olusegun Obasanjo said that the idea of Biafra separating from Nigeria is "dead."
Femi Fani-Kayode said "all hell will break loose" if the high-profile prisoners are harmed.