Nigerian police has made "some arrests" in connection with its probe into last week's suicide bombing at the UN headquarters building in the country, that killed 21 people.
However, the country's Inspector General of Police, Hafiz Ringim did not reveal their identities, number or nationalities.
"I wish to inform you that our security agencies have made some arrests and His Excellency (President Goodluck Jonathan) would soon make pronouncements in that regard to you," he said.
The attack killed at least 21 people when a suicide bomber made his way through two gates and rammed into the entrance of the heavily guarded building in one of the bloodiest attacks targeting the UN.
The officer added that all security agencies in the country have been ordered by the President to liaise with foreign missions operating in Nigeria to ascertain their security needs for their staff and facilities.
"It is in that regard therefore that I was asked to appear before you and try to explain some of the things that has happened and also government's decision as far as security of yourselves and your missions are concerned.
"To start this we have assessed the threats not only in this country but to the entire sub-region West Africa," he said.
Ringim assured the diplomatic community in Nigeria of their safety.
Radical Islamist sect Boko Haram had claimed responsibility for the Friday attack, in which a suicide bomber blew himself up after driving his car into the building.
The group has threatened more of such attacks.