The judge, Binta Nyako, adjourned hearing in the case till that date to rule on the applications.
CHANNELS Television reported that the court also reserved April 6 to hear the application seeking variation on its earlier ruling on protection of witnesses in the matter through the use of screen or mask.
Justice Nyako told the defendants that in spite of their applications, she would not change her mind on the protection of witnesses, as long as they remain with security operatives.
According to the judge, their participation in the case is part of their duties, as such she would not expose them because of future engagement.
The defendants however insisted that they would still bring their application on the ground that her quashing of six out of the earlier eleven charges, has made the case a fresh one.
They say they were inclined to seek for a variation on the witness protection order.
Nnamdi Kanu, a director of Radio Biafra, is currently remanded in Kuje prisons by the State Security Service, SSS.
Mr. Kanu is charged alongside three others, David Nwawuisi, Benjamin Madubugwu and Chidiebere Onwudiwe, with treasonable felony by the Nigerian government for leading the IPOB movement to ask for an independent Biafra out of Nigeria.
The Federal High Court sitting in Abuja recently struck out six out of the 11-count charges filed against the defendants for being incompetent.