Kano - Boko Haram appears to have been weakened by a sustained regional fight-back but there are growing fears the group could target vulnerable people displaced by the violence, as elections approach.
More than 13 000 people have been killed in the bloody six-year insurgency, with some 1.5 million more forced to flee their homes within Nigeria and abroad.
Security analysts have warned that with the Islamists hit hard by the coalition of Nigeria, Niger, Cameroon and Chad, the group will revert to guerilla tactics of bombings and suicide attacks.
There has already been a spate of suicide bombings against "soft" targets such as markets and bus stations since the turn of the year.
Now, it is feared that internally displaced people (IDP) could be next, after Boko Haram leader Abubakar Shekau vowed to disrupt this Saturday's elections, which the group views as "un-Islamic".
"Boko Haram are very likely to hit back in a way that will hurt Nigeria and IDP camps are possible targets," Abdullahi Bawe Wase, a security analyst who tracks the conflict, told AFP.
Scores of IDP camps dot Maiduguri following a huge influx of people fleeing towns and villages seized by Boko Haram, doubling the population of the Borno state capital to at least two million.
Last Monday, the head of Nigeria's electoral commission INEC, Attahiru Jega, said 20 percent of the estimated one million IDPs were in camps and arrangements had been made for them to vote.
"We have found stable places in most cases outside the camps, except in Maiduguri, where in a few places we have placed (polling stations) inside the camps for security reasons," he said.
Elements
Yet even here safety is an issue, with the discovery on 14 March of three explosive devices at the Yerwa Primary School camp.
A fourth explosive device has yet to be located, as the suspects forgot where it was planted, said Ari Butari, a local civilian vigilante involved in camp security.
Eight people were arrested and two allegedly confessed to planting the devices. They were living among the IDPs, many of whom fled from the state's second largest city, Bama, last September.
"We are really apprehensive about our security since the discovery of the explosives," said Babakura Kyarimi, who lives in the camp.
"It is a clear indication that there are Boko Haram elements in our midst, which is of serious concern to us and the authorities."
The discovery backs up previous claims about the danger of Boko Haram infiltrating the camps, including from the Roman Catholic Diocese of Maiduguri last August.
In January, troops detained as a precaution thousands of people who left the garrison town of Monguno on the outskirts of Maiduguri to establish whether rebel fighters were among them.
The Kano state government also shut a camp it had opened for people displaced from the town of Mubi in Adamawa, after a Boko Haram insurgent was uncovered.
Political motives for the discovery of explosives in the IDP camps cannot be ruled out, with Nigeria's northeast an opposition stronghold.
Bomb planting
"One cannot dismiss the political element in the Boko Haram insurgency and the planting of bombs in an IDP camp could be a ploy by politicians averse to holding elections in camps because it doesn't favour their political interest," said Wase.
"It could be intended to instil fear in IDPs ahead of the elections to leave the camps, now that it's clear elections are to be held in camps."
Debate about whether IDPs should vote in camps or return to their home towns and villages has been a major point of political debate between Nigeria's two main political parties.
But with infrastructure non-existent and communities devastated by the violence, the Borno Elders Forum of retired senior civilian and military officials has warned against any premature return.
Last week, scores of Boko Haram killed 11 people in the Borno town of Gamboru after Chadian troops withdrew, in a clear sign that the militants still have the capacity to attack.
"We think it is too early to even start talking about anyone going back to any of these reclaimed territories," the body's chairman, Usman Gaji Galtimari, said in a statement last week.
"I think it will be irresponsible on our part as a government to hurry our citizens back to liberated communities now mainly to go and vote," added Borno state governor Kashim Shettima.
"We all know that these liberated communities are still not fully safe and habitable."
AFP