ABUJA (Reuters) - Nigerian President Goodluck Jonathan vowed on Saturday to catch those behind a New Year's Eve bombing that killed at least four people, part of a wave of violence testing his grip weeks before a presidential primary.
There has been no claim of responsibility for the attack and the president said the perpetrators had not yet been identified.
"The security people are on it. We will get to the root of the matter. I urge Nigerians to remain calm," Jonathan said speaking at a New Year's Day church service in Abuja.
"To me they are pure criminals that demons are using these days, not only in Nigeria but also in acts of terrorism across the whole world."
Islamist militants based in the north and rebels from the oil-rich Niger River delta in the south have both claimed responsibility for bombings in Nigeria in recent months.
Jonathan had said on Friday that those behind the Abuja blast were the same as those behind Christmas Eve bombings in the central city of Jos, which were claimed by the Islamist sect Boko Haram. On Saturday however the presidency said Boko Haram had not at this stage been linked to the Abuja bomb.
The flare-up of violence has come at a bad time for Jonathan, who inherited the office when President Umaru Yar'Adua died in May and will contest ruling party primaries in January in a step toward April's presidential election.
Jonathan can ill afford a security crisis, as any unrest in Africa's most populous nation is likely to be used by his rivals to undermine his credibility.
WASHINGTON OFFERS TO HELP
The Abuja blast occurred at a busy market area where people congregate to socialize on the edge of an army barracks.
"Three men and one pregnant lady have been confirmed dead, while 26 other injured people are receiving treatment," Nigeria's Defense minister Tokunbo Olukayode said.
President Barack Obama said Washington was prepared to help track down the perpetrators.
"Killing innocent civilians who were simply gathering -- like so many people around the world -- to celebrate the beginning of a New Year further demonstrates the bankrupt vision of those who carry out these attacks," he said.
Senator Bala Mohammed, the Minister of the Federal Capital Territory (FCT) which includes Abuja, said the attackers' aim was to create panic, make April general elections impossible and incite the military to intervene.
"This is a case of using innocent blood and human lives to do politics," Mohammed said in a statement on Saturday.
INCREASE IN VIOLENCE
Police say the Christmas Eve church bombings in Jos and ensuing violence between Christians and Muslims there killed 80 people. Boko Haram also claimed responsibility for bombing churches in the northern city of Maiduguri on Christmas Eve and police say at least 16 people have died in attacks by the group there in the past week.
A Niger Delta rebel group claimed responsibility for car bomb attacks in Abuja that killed at least 10 people in October.
Nigerian elections usually favor the incumbent and Jonathan is still the frontrunner, but his campaign is controversial.
An unofficial party pact says that power within the ruling People's Democratic Party (PDP) should rotate between the mostly Muslim north and largely Christian south every two terms.
Yar'Adua, a northerner, died during his first term, and some northern factions are opposed to the candidacy of Jonathan, a southerner. He faces a northern challenge from former Vice President Atiku Abubakar for the party nomination.