At least 10 people have been killed in an apparent suicide car bombing at the UN building in the Nigerian capital Abuja.
The powerful blast wrecked the bottom floor of the building. Dozens have been injured, some critically.
A UN official in Nigeria, who spoke to the BBC on condition of anonymity, said the UN had received information last month that it could be targeted by Islamist group Boko Haram.
Security was stepped up in response.
A car bombing at police headquarters in June was blamed on Boko Haram, a group which wants the establishment of Sharia law in Nigeria.
