(http://news.bbcimg.co.uk/media/images/74253000/jpg/_74253710_nigeriachibok4640414.jpg) President Goodluck Jonathan's government says 5,000 police and soldiers will be deployed for the World Economic Forum on Africa (http://www.weforum.org/events/world-economic-forum-africa-0), which begins on Wednesday.
Chinese Premier Li Keqiang and the presidents of Rwanda, Senegal and Kenya will be among international as well as African figures at the forum.
While the official reason for closing all schools and government offices in Abuja is to ensure traffic flows smoothly, tightening security is also a likely reason, the BBC's Will Ross reports from the Nigerian capital.
Fewer vehicles on the roads should enable stricter searches and cut the number of potential targets for further bomb attacks, he adds.
"The government has taken the strongest measures to ensure a safe forum. We ask participants not to let terror win," Finance Minister Ngozi Okonjo-Iweala said in a statement.
In a separate development, the US embassy has warned its citizens of a planned "unspecified attack" on one of two Sheraton hotels in Lagos.
The finance minister said the security measures were aimed at calming nerves but told Nigerian media the focus on returning the abducted girls to their families was "much more important".
(http://news.bbcimg.co.uk/media/images/74605000/jpg/_74605176_022103040-1.jpg) Protests have been held calling for more to be done to save the girls (http://news.bbcimg.co.uk/media/images/74603000/jpg/_74603703_74601730.jpg) Relatives of the abducted girls have received little information about the rescue effort Boko Haram has not made any response to the accusation that its fighters abducted the girls from the school in Chibok town in the middle of the night on 14 April 2014.
Since the kidnapping, parents have criticised the government's search and rescue efforts.
The police chief in Borno state has put the number of missing girls at 223 and has appealed to parents to come forward with photographs of their daughters to confirm who has been seized. According to the police commissioner, 53 of the girls are believed to have escaped.
It is thought that the militants initially took the girls to the Sambisa forest; there have been subsequent reports they have been taken over the borders into Chad and Cameroon and possibly forced to "marry" the insurgents.
(http://news.bbcimg.co.uk/media/images/74436000/jpg/_74436147_74436140.jpg) The girls were seized from their school late at night (http://news.bbcimg.co.uk/media/images/74561000/jpg/_74561805_74561483.jpg) These four students were among those who managed to escape after being abducted
Source: BBC.co.uk