Nigerian authorities have banned public protests in the capital Abuja for the release of more than 200 schoolgirls seized by Islamist militants in April.
Abuja police commissioner Joseph Mbu said the rallies were “now posing a serious security threat”.
Nigeria has seen almost daily rallies calling for the government to take firmer action to rescue the girls.
Boko Haram militants snatched the girls from the remote Chibok village near the Cameroon border on April 14.
Nigerian authorities have banned public protests in the capital Abuja for the release of more than 200 schoolgirls seized by Islamist militants (photo AP)
In a statement, Joseph Mbu said that public protests had “degenerated” and were now a security threat.
He was also quoted by the state-run Agency of Nigeria as saying that “dangerous elements” could join the demonstrations.
Nigeria’s government has been facing growing pressure both at home and abroad to do more to tackle the group and bring about the girls’ release.
A deal for the release of some of the abducted schoolgirls in Nigeria was close to being secured when the Nigerian government called it off late last month.
Some of the girls were set to be freed in exchange for imprisoned Islamist militants.
Thousands of people have died since Boko Haram began a violent campaign against the Nigerian government in 2009 and in the subsequent security crackdown.
The girls, who were mainly Christian, were taken from their school in Chibok, in north-eastern Borno state and are thought to be held in a remote forested area of the state, close to the border with Chad and Cameroon.
The Nigerian government has decided to shut schools and government offices across the capital Abuja, while a World Economic Forum conference takes place next week.
A big security operation is being promised to protect more than 1,000 delegates at the three-day meeting, after two deadly bomb attacks in Abuja.
An explosion late on Thursday killed 19 people, two weeks after a nearby bombing left 75 dead.
Islamist militant group Boko Haram is being blamed for the violence.
The same group is believed to be behind the kidnapping of more than 200 teenage girls from their school in Borno state in north-eastern Nigeria more than a fortnight ago.
The World Economic Forum Annual Meeting 2014 will take place in Abuja from May 7 to May 9
The group, whose name means “Western education is forbidden” in the local Hausa language, has staged a wave of attacks in northern Nigeria in recent years, with an estimated 1,500 killed in the violence and subsequent security crackdown this year alone.
President Goodluck Jonathan’s government says 5,000 police and soldiers will be deployed for the World Economic Forum on Africa, 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.
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”.
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 April 14.
Since the kidnapping, parents have criticized 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.
At least six people have been killed in two explosions at the offices of major Nigerian daily ThisDay, according to witnesses.
Three people were killed in a blast in Abuja, with another three killed at the paper’s offices in the northern city of Kaduna.
Witnesses say at least one was a suicide bombing, but officials say it is too early to say.
No-one has said it carried out the blasts although the Islamist group Boko Haram has staged similar attacks.
Both blasts are reported to have occurred at the offices of the ThisDay newspaper, a Nigerian leading daily.
At least six people have been killed in two explosions at the offices of major Nigerian daily ThisDay
Details remain sketchy but several witnesses, including the chairman of ThisDay‘s editorial board, said the blasts were the result of a suicide attack.
“The suicide bomber came in a jeep,” Olusegun Adeniyi told reporters at the scene in Abuja.
“[Security guards] opened the gate for them… The guy drove in through the gate and rammed into the building and exploded,” Olusegun Adeniyi said.
However, a spokesperson for Nigeria’s National Emergency Management Agency earlier said the Abuja blast appeared to be caused by a bomb planted inside the building.
The Kaduna explosion happened outside a complex housing a number of newspapers, including ThisDay.
A suspect has been arrested and is thought to be a member of the Boko Haram group, news agency AFP reports police as saying.
Footage filmed by the Nigerian paper the Daily Trust, showed a scene of confusion in Abuja as people sifted through the rubble as a number of small fires burned.
Police and paramilitary forces have cordoned off both offices, while emergency workers evacuated the injured and removed the bodies of those who died, witnesses say.
“The ceiling of our building collapsed on to our computers because of the force of the blast,” said an Abuja office worker in the building next door to ThisDay.
Boko Haram – whose name means “Western education is forbidden” – wants to establish Islamic law in Nigeria and has launched a series of deadly attacks across the country, including the capital, in the past 19 months.
Last month the group warned journalists not to misrepresent their views.