Friday’s car bomb blew out windows, gutted a lower floor and set the building alight in one of the most lethal attacks on the world body in its history.
There has been no confirmed claim of responsibility for the attack but security sources suspect the violent Islamist sect Boko Haram, which has been blamed for almost daily bomb and gun attacks on security forces and civilians in the northeast.
A U.N. spokesman accompanying Migiro at the hospital where the victims were being treated said the death toll had risen to 23, from an earlier estimate of 19 given by emergency services.
That would make it more deadly than the truck bomb attack on the U.N. headquarters in Baghdad in 2003 that killed 22 people, including U.N. envoy Sergio Vieira de Mello.
“We are working as a team to ensure that the injured do get all the treatment that they require,” Migiro said after visiting the hospital, where she shook hands and patted the backs of the wounded.
“For people who had lost their lives we are working to see how they are going to be put to rest,” she said.
Migiro was due to meet later on Sunday President Goodluck Jonathan, who visited the bomb site on Saturday but declined to speculate on who could be behind the attack.