Nigeria asked the U.N. Security Council to impose sanctions on Boko Haram, the armed Islamist group that claimed the kidnapping of more than 200 schoolgirls, and list it as a terrorist group, diplomats said Tuesday.

They said Nigeria lodged the request with a Security Council committee that deals with sanctions against al-Qaida-linked groups.

Two men have been arrested in connection with a suicide car bombing in the northern Nigerian city of Kano that killed four, police said on Tuesday.

"Two suspects are now in custody in connection with Sunday's bombing in Sabon Gari," Kano police spokesman Musa Magaji Majia told Agence France Presse.

Twin car bombings killed 46 people on Tuesday at a crowded market in the central Nigerian city of Jos, as emergency workers struggled to contain a raging fire, officials said.

"For now, we can authoritatively confirm that 46 people were killed in the blasts while 45 people were seriously injured," said Chris Olakpe, the police commissioner in Plateau state.

Nigeria's parliament on Tuesday approved a six-month extension to a state of emergency in three northeast states hit by Islamist militant violence.

Senators unanimously approved the continuation of special powers in Adamawa, Borno and Yobe states in a vote, following a similar backing from the lower chamber House of Representatives last week. 

Nigeria's police on Tuesday announced plans to beef up security at the country's boarding schools in direct response to the mass abduction of more than 200 schoolgirls by Boko Haram militants.

"The Inspector General of Police, MD (Mohammed) Abubakar, has ordered command commissioners of police to immediately commence (a) security audit and threats analysis of all boarding schools nationwide," the police said in a statement.

Israel has sent two anti-terror experts to Nigeria to join the search for hundreds of schoolgirls kidnapped by extremist Islamist group Boko Haram, an Israeli security source said on Tuesday.

"There are in Nigeria two advisers who have dealt in terrorist matters in the past," he told Agence France Presse. "They were sent there by the state to help."  

Britain's Ministry of Defense on Monday said that a spy plane sent to help in the search for the Nigerian schoolgirls kidnapped by Islamists had been grounded en route due to a fault.

"A technical fault which has delayed the Sentinel aircraft on its way to Ghana is being investigated and will be solved as soon as possible," said an MoD statement.

Police said on Monday they had foiled a second suicide car bomb attack in Kano, after a blast ripped through a busy entertainment spot in Nigeria's second city, killing four.

The authorities said it was too early to say who was behind the first blast in the predominantly Christian Sabon Gari district, which has previously been targeted by Boko Haram militants.

Four people were killed, including a young girl, in a suicide car bomb attack in the north Nigerian city of Kano on Sunday, the city's police commissioner said. 

"At about 2200 (2100 GMT), we heard an explosion and immediately mobilized to the scene where we discovered a suicide bomber... five people, including the bomber, were killed," said Adelere Shinaba. 

France's foreign minister offered China his country's help on Sunday in locating 10 workers feared kidnapped by Boko Haram militants, as African leaders joined forces to fight the terrorist group.

"We have already told our Chinese friends that we were at their disposal in helping them find their citizens," Laurent Fabius said on a visit to the Chinese capital, where he will meet Prime Minister Li Keqiang on Monday.