ABUJA (Reuters) - Nigeria's military is losing control of swathes of the largely Muslim northeast to radical Islamist insurgents who are killing civilians almost daily, and the run-up to elections next year risks aggravating the violence further.
Islamist sect Boko Haram has killed thousands since it launched an uprising in 2009 in a bid to carve out an Islamic state in the West African country of 170 million people, divided roughly equally between Christians and Muslims.
More than 150 civilians have died in Boko Haram attacks in the last four days, adding to the 300 killed last month, according to Reuters figures and security sources, one of the worst periods in the northeast since the sect intensified its insurgency three years ago.
A security source, who asked not to be named, said 2,100 people were killed in Boko Haram violence in the last six months.
Nigeria - Africa's biggest oil producer and second largest economy - is a year away from a presidential election and already the two main political parties are trading blame over the escalating Boko Haram conflict.
President Goodluck Jonathan, who is expected to run for re-election in next February's vote, declared a state of emergency in three north-eastern states last May and launched a military surge into the zone. It has failed to stem the bloodshed.
Elections are often violent periods in Nigeria and politicians have in the past paid armed groups to destabilise regions, which could allow Boko Haram the opportunity to extend its insurgency towards the nation's centre.
"The north-east is likely to witness some of the highest levels of violence during the elections given that fierce political competition will overlay existing insecurity," said Roddy Barclay, Nigeria analyst at Control Risks.
"But perhaps the greatest risk stems from Boko Haram taking advantage of any outbreak in post-election unrest to incite ethno-religious violence in the north," he said.
Boko Haram is increasingly targeting the civilian population and caused international outrage when dozens of school children were slaughtered in an attack last month. Young girls are regularly kidnapped by insurgents.
The mounting bloodshed in the Muslim-dominated, less developed north has prompted Jonathan's opponents to question whether as a southern Christian he understands the severity of the Boko Haram threat. Jonathan says it is a top priority.
In the past, some southern politicians have accused northern political power brokers of stoking the Boko Haram revolt to undermine Jonathan because they oppose his standing for next year's polls. Since independence, Nigeria's delicate internal political and ethnic balance has been maintained by rotating the presidency between northerners and southerners.
Western governments are concerned about Boko Haram taking total control of northeast Borno state, which borders Niger and Cameroon and could provide a base for the sect joining up with al Qaeda-linked groups in the unstable Sahel region.
Jakkie Cilliers, executive director at the Pretoria-based Institute for Security Studies, said the scale of Boko Haram's attacks in the northeast and the slaughter of civilians there suggested a calculated intent to sow terror.
"The purpose of terrorism is to terrorise and destroy, so that it becomes a no-go area, so that the population are simply too terrified, and you create a separation within the body politic that is unresolvable," he told Reuters.
Borno State Governor Kashim Shettima has said Boko Haram is far better equipped than the Nigerian military. Dozens of witnesses have given accounts this year of soldiers fleeing before insurgents attack or being outnumbered and outgunned.
Internet videos posted by Boko Haram show they have seized large quantities of arms and military equipment. Images often show armoured cars mounted with 50 caliber guns, while fighters wear bullet-proof jackets, armed with AK-47 rifles and grenades.
"Boko Haram is getting the upper hand each day. The spate of killing is getting worse," said Bishop Oliver Dashe Doeme, who is based in Borno state.
"The equipment the military are using is not sufficient. They need modern weapons to curtail the insurgents," he said.
Nigeria's armed forces did not immediately respond to requests for comment.
In statements last week, the military said its operations in the northeast were proving successful, killing 13 insurgents recently and arresting many more in a series of raids.
Boko Haram fighters have focused their attacks in rural areas to the south and east of Maiduguri, Borno's capital, although there have recently been bomb attacks in the city.
At least 3,000 insurgents are based in the Sambisa Forest, south of Maiduguri, with a similar number in the mountain region on the Cameroon border, security sources told Reuters, adding these are difficult areas for the military to secure.
"You can understand why exposed and under supported military units wouldn't want to take on assaults by Boko Haram, which can often involve 100-150 heavily armed, steadfast fighters," a Western diplomat who analyses the military said.
But with the largest standing army in sub-Saharan Africa and 20 percent of the federal budget allocated to security - around $6 billion - many Nigerians question whether the army is being properly managed in a country rife with corruption.
"The Nigerian Army top command must provide answers to questions being asked by Nigerians. Why is Boko Haram always attacking when they are supposed to be on the run? Why are our troops always on the defence?" a statement from the Muslim Rights Concern, a non-government organisation, said last week.
In its 2013 Conflict Barometer, the Heidelberg Institute for International Conflict Research categorises the Nigerian government's conflict with Boko Haram in Borno state as a "war", as opposed to a "limited war" or "violent crisis".
Many analysts believe the longer-term threat of instability is underestimated because it appears far removed from central Nigeria, where the capital Abuja is located, and from the commercial hub of Lagos and oil-producing areas in the south.
"When you speak to Nigerians and investors, they often very rapidly discount what is happening, all the attention is on the growing consumer market," Cilliers said.
"This has the potential to really hobble Nigeria."
(Additional reporting by Lanre Ola in Maiduguri, Felix Onuah in Abuja and Pascal Fletcher in Johannesburg; Editing by Pascal Fletcher and Angus MacSwan)