The death toll following the suicide bombing of UN headquarters in Nigeria has risen to 23, with 81 wounded, a spokesman for the world body said in Abuja on Sunday.
"The latest casualty is 23 dead, 81 wounded," Martin Dawes told journalists of the attack on Friday that left much of the building gutted.
Deputy UN Secretary-General Asha-Rose Migiro visited the destruction of the world body's headquarters in Nigeria on Sunday, calling the suicide bombing there an attack "against humanity". "I've come to assess the situation," she said after touring the heavily damaged building in the Nigerian capital Abuja following Friday's attack.
"It is a shocking incident. This attack is against global peace. It is also against humanity because those who work here come from different countries."
The UN's deputy chief vowed a renewed push to fight terrorism after the suicide bombing of the world body's headquarters in Nigeria that left at least 19 dead as she prepared for talks here on Sunday.
Friday's attack, that saw the bomber make his way through two gates at the heavily guarded compound before slamming his car into the entrance of the building, was among the bloodiest targeting the UN globally.
"We condemn it in the strongest terms, but this act of terrorism will only rekindle our resolve to fight terrorism in all of its ramifications," Migiro told journalists after arriving, calling the attack "terrible." UN security chief Greg Starr was also in Nigeria and meetings were being held with United Nations officials early Sunday.
Migiro was due to visit the UN building, then the national hospital to speak with some of the wounded. She will also meet President Goodluck Jonathan and United Nations staff later in the day.
Questions swirled over how the bomber managed to pass through two gates in the exit lane of the compound as well as over who was responsible for the blast in the continent's largest oil producer.
A purported spokesman for the Nigerian Islamist sect known as Boko Haram has claimed responsibility for the attack, but there has been no proof and police say they are considering all possibilities.
Analysts have cautioned that while at least one faction of the sect may indeed be involved, it was too early to draw any firm conclusions. Boko Haram has previously focused on targeting symbols of Nigerian authority, but its attacks have grown increasingly sophisticated and concerns have grown over whether it has formed links with Al-Qaeda's north African branch or other extremist groups.
The United Nations has said nine of its staff were confirmed dead and "many dozen hospitalised," but warned it was still assessing the toll, which did not include non-UN staff, such as security and visitors.
"We have lost motivated, bright, selfless people who were working only for the good of Nigeria and the world," said Agathe Lawson, the UN's acting resident coordinator in Nigeria. "Our priority now is to ensure those who are injured and the families of those who died are cared for."
She added that "our second and urgent priority is to ensure the UN operations continue. We will not be deterred in our mission to work to improve the lives of Nigerians. This is why we are here."
It was believed that everyone had now been evacuated from the building, with much of the lower floors gutted from the blast.
A bomb blast that rocked a car park at national police headquarters in Abuja in June and killed at least two people was claimed by Boko Haram.
Police first said it was the result of a suicide blast before later retracting their statement, saying they could not be sure. Most of the attacks blamed on the sect have occurred in the country's northeast, but a number have been carried out elsewhere, including the previous explosion in Abuja as well as several in Suleija near the capital.
The Islamist sect launched an uprising in 2009, put down by a brutal military assault that left hundreds dead. It went dormant for about a year before re-emerging in 2010 with a series of assassinations of security personnel and politicians, as well as religious and community leaders.
Nigeria's 150 million population is roughly divided in half between a mainly Muslim north and predominately Christian south.