Lagos, Nigeria (CNN) -- The court date of a man held after deadly bombings in Nigeria has been postponed because of fears about his safety in custody, his lawyer said Monday. 

Henry Okah is being held in a Johannesburg, South Africa, prison, but his lawyer, Rudi Krause, wants him separated from the general prison population for his safety, he said. 

He is being charged under terrorism legislation, Krause said. Extradition has not been discussed, he added. 

The prosecutor and police have applied for the hearing to be postponed to Tuesday morning, the lawyer said. 

Okah is suspected of being an influential member of the group that took responsibility for the bombings that killed 12 people and injured 50 in Nigeria on Friday. 

The Movement for the Emancipation of the Niger Delta, known as MEND, issued a statement Saturday saying it had given the Nigerian government advance warning. 

The Nigerian Intelligence Service said Monday that nine people have been arrested and are being questioned in connection with the blasts Friday in the nation's capital, Abuja. Authorities are still seeking two men, identified as Chima Orlu and Ben Jessy, whom they accuse of being the "masterminds" of the plot. 

But sources close to MEND told CNN that the two men are "not known to be MEND operatives or known to be active on the Niger Delta issue." 

They also raised concerns about the nine other arrests, calling them an "attempt by the Nigerian government to be seen to act." 

Nigerian President Goodluck Jonathan has appointed Andrew Azazi, his former chief of defense staff, to be the country's national security adviser in the wake of the bombings, Jonathan's office told CNN on Monday. 
From who?
the general prison population