Security was increased around the Federal High Court on Monday ahead of the resumption of the trial of Nnamdi Kanu.
According to a Channels Television correspondent, major entrances to the court were blocked.
Mr Kanu is the leader of the Indigenous People of Biafra (IPOB), a group seeking the breakaway of a significant chunk of southern Nigeria, to form a Republic of Biafra.
Policemen sighted along the road to the Federal High Court in Abuja on July 26, 2021.
He was first arrested by Nigerian authorities in 2015 on an 11-count charge bordering on “terrorism, treasonable felony, managing an unlawful society, publication of defamatory matter, illegal possession of firearms and improper importation of goods, among others.”
The Federal Government is expected to bring new charges against him on Monday.
Rearrested for trial
Mr Kanu had fled Nigeria in 2017 after he was granted bail for medical reasons.
He fled after an invasion of his home by the military in Afara-Ukwu, near Umuahia, Abia State.
Before his re-capture by Nigerian authorities, he had been sighted in Israel and had continued to rally his supporters in Nigeria to employ violence in achieving secession.
Kanu was intercepted on June 27 and was repatriated to Nigeria in a shadowy operation conducted by Nigerian security operatives in collaboration with international partners.
The Nigerian government has promised to grant him a fair trial.