Abuja: Nigerian police named two men as masterminds of two deadly independence day car bombings after President Goodluck Jonathan said a "small terrorist group" based abroad was behind the attacks.
Police said on Sunday the perpetrators had intended to "commit mass murder" and distributed photos and other details of the two suspects, identifying them as Nigerian citizens Chima Orlu and Ben Jessy.
"An arrest has been made by the police in connection with the incident," the police statement said.
It also provided a death toll of 10 from the blasts, despite Abuja police having given the figure as 12.
The attacks near celebrations marking the west African nation`s 50 years of independence were followed by a claim of responsibility by Nigeria`s main rebel group.
But Jonathan said the perpetrators were "a small terrorist group that resides outside Nigeria that was paid by some people”.
"We are on their trail and I promise Nigerians that the matter will be investigated to the last, and until everybody that is connected is brought to book, we will not rest. Government will no longer condone this culture of impunity."
Statements in the name of Nigerian militant group MEND have claimed responsibility for the bombings, but Jonathan seemed to cast doubt on the author of the claim.
"There was a statement purported to have been written by MEND, but investigations show that members of MEND have said they don`t know about it," the President said.
"Anybody who thinks that he can come under the cover of Niger Delta struggle to perpetrate violence and criminality, your time is over. We will no longer tolerate it, we will not accept it, the security agents are on their trail, and Nigerians will soon know the actors behind this evil."
MEND -- the Movement for the Emancipation of the Niger Delta -- has claimed to be fighting for a fairer distribution of oil revenue.
It has carried out scores of attacks in the Niger Delta, the country`s main oil-producing region, but an amnesty deal offered by the government last year has greatly reduced the unrest.
The group, which has been seen as an umbrella organisation for criminal gangs and which police have called "amorphous", had never before struck in the capital and rarely caused such a high number of casualties.
The attack also came ahead of elections due early next year.
A statement attributed to MEND sent to media outlets about an hour before the bombs went off warned of the attacks. Further statements claimed responsibility and said authorities were given a five-day advance warning.
The statements are always signed by Jomo Gbomo, believed to be an alias, and come from the same email address.
A spokeswoman for the Nigerian intelligence service said authorities were aware of warnings purportedly from the group a number of days before the blasts and security was tightened.
After the attacks, an ex-MEND leader, Henry Okah, was arrested in South Africa under the country`s terrorism and related offences laws. He has not yet been charged and is due to appear in court on Monday, his lawyer said.
He has denied any involvement in the car bombings, according to his lawyer, Piet du Plessis.
Okah was arrested in Angola three years ago and later transferred to Nigerian custody. He was released last year as part of the amnesty programme and has a home in South Africa.
Another statement in the name of MEND on Saturday said that "Okah has never been involved in any MEND operations but has always been blamed for every attack, which is strange to us".