Prosecutors did not say what new charges they planned to introduce against the Nigerian national, already accused of terrorism, conspiracy to commit terrorism and discharge of explosives in connection with blasts that killed 12 people in Abuja during Independence Day celebrations on October 1.

Okah, who has permanent residence in South Africa, appeared briefly in a Johannesburg court Monday. His case was postponed to June 21 for further investigation and for prosecutors to prepare the new charges.

Prosecutors say Okah is the leader of the Movement for the Emancipation of the Niger Delta (MEND), a militant group in Nigeria’s oil-rich Delta region that claimed responsibility for the attacks.

They say he exchanged messages and phone calls with people the Nigerian authorities believe carried out the bombings, and that he gave orders to buy the two cars and fill their trunks with dynamite.

Okah, who is fighting for his release but has twice been denied bail, says he has never been the leader of MEND and denies the charges against him.

His court appearance comes as votes are tallied from Nigeria’s Saturday elections, which President Goodluck Jonathan — the country’s first leader from the Delta region — appeared poised to win.