File photo: US Secretary of State John Kerry. (Associated Press)
Nigeria's military fought Boko Haram militants in the restive northeastern city of Maiduguri on Sunday, as US Secretary of State John Kerry jetted in to discuss fears about election-related violence.
Militants launched a dawn raid on Jintilo village on the outskirts of the Borno State capital, prompting soldiers to respond with heavy weaponry and air support while the authorities to put the entire city on lock-down.
At the same time, Islamist fighters attacked Monguno, about 65 kilometres (40 miles) from the fishing town of Baga, where hundreds, if not more, people were killed in a devastating Boko Haram onslaught earlier this month.
The renewed violence underscored the extent of the difficulties facing Nigeria as it scrambles for a solution to enable hundreds of thousands of people displaced by the unrest to vote next month.
It also demonstrated the uphill battle facing President Goodluck Jonathan, who was at a campaign rally for the February 14 election in Maiduguri on Saturday, where he again vowed to end the six-year insurgency.
Close cooperationKerry was due to meet Jonathan and the main opposition's presidential candidate, former military ruler Muhammadu Buhari, in the financial capital Lagos.
The visit - the first to Nigeria by a US secretary of state since Hillary Clinton in 2012 - was announced on Friday during a speech in which Kerry warned of the dangers of Islamist extremists.
Kerry has previously described the attack on Baga as a "crime against humanity" while the United States has warned of the threat to Nigeria's sovereignty posed by the militants, who want to create a hardline Islamic state in northeast Nigeria.
A senior US official told reporters travelling with Kerry that the insurgency, which is increasingly threatening neighbouring countries, would likely be raised with both candidates.
"We have been working very, very closely with the government of Nigeria to address Boko Haram, and I can say very clearly that no country has done as much as we have to support Nigeria's efforts," the official said.
"And we would hope that both candidates will be able to address the insecurity and address Nigeria's response to Boko Haram."
But US involvement in Nigeria has been fraught, with criticisms in particular of the Nigerian government's slow response to the mass abduction of 276 girls from the town of Chibok in April last year.
US drones were deployed and the Pentagon dispatched intelligence and surveillance specialists in the hope of finding the 219 teenagers still being held but to no avail.
Assistant Secretary of State Linda Thomas-Greenfield has accused Nigeria's military of being in denial about the threat posed by Boko Haram, which has captured dozens of towns in the last six months.
Nigeria's ambassador to Washington has accused the United States of failing to provide the weaponry required to end the rebellion and Abuja also ended a US training programme for soldiers to take on the militants.
But despite massive defence spending accounting for some 20 per cent of the federal budget last year, Nigerian troops maintain that they lack the right weapons and equipment to take on the better-armed militants.
'The world is watching'
Boko Haram is thought to have increased the scope and intensity its attacks since the turn of the year to further undermine the credibility of the government, which it sees as illegitimate and un-Islamic.
But Kerry was instead expected to address poll-related violence, which has blighted Nigerian elections in the past and which it is feared could erupt again, given the close race between the two candidates.
Some 1,000 people died at the last elections in 2011 during protests in central Nigeria, where the predominantly Christian south meets the mainly Muslim north.
Both Jonathan and Buhari recently signed a non-violence agreement but that has not stopped sporadic outbreaks of unrest between supporters of their Peoples Democratic Party (PDP) and the All Progressives Congress (APC).
The US official said: "This election in Nigeria is being watched by the entire continent and in fact by the entire world.
"And we are all hoping and expecting and delivering messages to encourage that the election is one that is free and fair and most importantly peaceful, and that it is an election that reflects the will of the Nigerian voters."
The United States has pressed for the elections to go ahead, despite raging insurgency.
This week, Nigeria's national security adviser, Sambo Dasuki, called for polling to be delayed as 30 million voter cards had yet to be distributed. But the electoral body maintained it was on track.