Nigeria's President Jonathan Goodluck has visited Maiduguri, the capital of the restive Borno state, where the armed group Boko Haram have intensified their attacks and seized more territory over the past few months.

Jonathan's visit to the northeast region on Thursday comes weeks before the presidential polls in which he is seeking re-election. It is his first trip since a state of emergency was imposed in May last year.

His office said in a statement that the president met with troops involved in fighting the group as part of his "surprise visit".

The deadly violence has spiked in recent months with Nigerian military struggling to corner the armed group, which has vowed to establish an Islamic state in the country's northeast. There was a global outrage when more than 200 Nigerian girls were kidnapped by Boko Haram from the town of Chibuk in April last year.

Nigeria's leader has come under fierce criticism for his failure to crush the armed group. Over 13,000 people have been killed in the violence since 2009.

On Thursday, human rights group Amnesty International released satellite images showing what it said was "indisputable and shocking evidence" of the scale of last week's attack on two Nigerian towns by Boko Haram fighters.

Al Jazeera's Ahmed Idris reporting from Abuja, said most people saw Jonathan's trip as simply a political one.

"Since the Chibuk kidnapping, and even before that, there were massacres and violence and he didn't make the trip there.

"With elections coming up, he knew that if the opposition had gone before him, it would have been disastrous," our correspondent said.

'Working very hard' 

The president also visited hundreds of civilians who are staying in a camp in Maiduguri after fleeing Baga, a town in Borno, after Boko Haram fighters overran an army base there and slaughtered civilians.

Jonathan told a crowd of internally displaced persons (IDPs) that "the government is working very hard" to make sure they don't stay "for too long" in the camps.

"He told survivors that the military had assured him that Boko Haram would be overcome," our correspondent said. 

As Boko Haram steps up attacks in Nigeria that have led to the killings of more civilians, there is increasing talk that international military action, possibly including a multinational force, may be needed to help crush the insurgency in Africa's most populous country.

Nigeria's neighbours are already being shaken by Boko Haram's territorial expansion. Niger, Chad and Cameroon have seen flows of refugees into their countries.

On Thursday, Cameroon's President Paul Biya announced that Chad will send troops to aid his country's army fight Boko Haram fighters from Nigeria, a government spokesman said.

"Chadian President Idriss Deby Itno has decided to send a substantial contingent of Chadian troops to back the Cameroonian armed forces who have faced repeated attacks from the Boko Haram terrorist sect with courage, determination and vigilance," the Cameroonian spokesman said in a statement.

Source: Al Jazeera and agencies