Nigeria's Boko Haram threatens to sell kidnapped schoolgirls

People take part in a protest demanding the release of abducted secondary school girls from the remote village of Chibok, in Lagos May 5, 2014. [Photo/Agencies]

In a statement, Patience Jonathan denied local media reports that she had ordered Nyadar's arrest but urged the protesters in Abuja to go home, the state-owned News Agency of Nigeria said.

"You are playing games. Don't use school children and women for demonstrations again. Keep it to Borno, let it end there," the agency quoted her as saying.

Protests continued in Abuja on Monday and spread to Lagos, Nigeria's commercial hub in the southwest and geographically as far away from the region troubled by Boko Haram as possible.

Lagosians normally express a degree of shoulder-shrugging apathy about the violence plaguing the north, but on Monday hundreds gathered outside the Lagos state secretariat to demand security forces do more to rescue the girls.

"This is the beginning. Until the girls are back, we will continue. I think this is the first step and we will mobilise more and more people," said Charlotte Obidairo of Youth Empowerment and Development Nigeria, a non-governmental organisation.

Protests could become a major headache for the government if they continue and coincide with the WEF event, where security arrangements will involve some 6,000 troops.

At least two people were killed in an attack by suspected Boko Haram militants on a military police outpost in northern Cameroon on Monday, a government spokesman said. The group has been using Cameroon's Far North region as a base for attacks in Nigeria.

In a televised "media chat" on Sunday, President Jonathan pledged that the girls would soon be found and released, but admitted he had no clue where they were.

"Let me reassure the parents and guardians that we will get their daughters out," he said, adding extra troops had been deployed and aircraft mobilized in the hunt for the girls.

Britain and the United States have both offered to help track down the girls, but neither has given specifics.