Nigeria's president has condemned twin bombings in the central city of Jos, in which at least 118 people were killed.
Goodluck Jonathan said those behind the attack were "cruel and evil".
It is feared more bodies still lie under the rubble of buildings destroyed by the explosions, which targeted a crowded market and a hospital.
A state of emergency is in place in north-east Nigeria to fight an insurgency waged by the Islamist group Boko Haram.
Last month Boko Haram abducted 200 girls from a boarding school in the north-eastern town of Chibok.
The president said he was committed to fighting terrorism despite criticism that he has failed to ensure security.
'Enemies of progress'
His office described Tuesday's attack as a "tragic assault on human freedom".
"President Jonathan assures all Nigerians that [the] government remains fully committed to winning the war against terror and... will not be cowed by the atrocities of enemies of human progress and civilisation," it said in a statement.
He announced increased measures to tackle the militants, including a multinational force around Lake Chad which comprises a battalion each from Chad, Niger, Cameroon and Nigeria.
If this is once again the work of Boko Haram, it shows the Islamist extremist group's determination to expand its area of operation and prove that it can strike where it wishes, the BBC's Will Ross, in the Nigerian capital Abuja, says.
The second blast at a market and bus terminal came 30 minutes after the first, killing rescue workers who had rushed to the scene.
Witnesses described a grim scene of dead and badly injured people - some with their limbs blown off - as fires were still raging out of control eight hours after the attack.
The fires were being fuelled by flammable goods at the market, including rubber sandals, the National Emergency Management Agency (Nema) said.
Dozens of casualties were covered in grain that had been loaded in the second car bomb, witnesses said.
Most of the victims were reportedly women.
Nigeria is under renewed worldwide attention over its response to Boko Haram, especially given the global attention on the missing schoolgirls.
Analysis by Will Ross, BBC News, Abuja
Once again the explosions were meant to cause as many casualties as possible. Like the recent Abuja blasts, the victims are of different religions and were mainly people out on the streets struggling to earn a living.
It has been almost two years since the last attack on Jos - when several churches were bombed. Those attacks were seen as an effort by Boko Haram to spark clashes between Christians and Muslims in the often volatile Middle Belt region of Nigeria.
For more than 10 years this area has been the scene of violent clashes that have often been portrayed as religious conflicts even though they are rooted in competition over land, power and resources. There is, however, a risk that these latest bombings will spark reprisal clashes and religious leaders have appealed for calm.
Meanwhile critics have questioned the military's tendency to use conventional tactics to fight an enemy waging a guerrilla war - they argue that "soft power" strategies could also be used.
More than 2,000 people, most of them civilians, have been killed this year, according to Nema, human rights and monitoring groups.
Diplomats on Tuesday said Nigeria had asked a UN Security Council committee responsible for imposing sanctions against al-Qaeda-linked groups to nominate Boko Haram as a terrorist organisation.
Sporadic militant attacks in Cameroon, Chad and Niger have also heightened fears of a regional war.
Earlier this month, the Nigerian senate unanimously approved a six-month extension of a state of emergency in Adamawa, Borno and Yobe states.
Nigeria under attack
- 19 May: Suicide blast on a busy street in northern city of Kano kills four, including a 12-year-old girl
- 5 May: Boko Haram militants slaughter more than 300 residents in the town of Gamboru Ngala
- 2 May: Car bomb claims at least 19 lives in the Nigerian capital, Abuja
- 14 April: Twin bomb attack claimed by Boko Haram kills more than 70 at an Abuja bus station. The same day, the group abducts more than 200 schoolgirls from the remote northern town of Chibok
- 17 March: At least 20 people die in a suicide car bomb at a bus stop in Kano
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