At least 118 people have died after twin car bombs exploded at Terminus market in the central Nigerian city of Jos on Tuesday, the National Emergency Management Agency said, raising the death toll from 46 reported earlier.
The second bomb killed some rescuers who were working in the billowing black smoke at the scene, with witnesses believing it was timed to explode half an hour after the first.
The explosives in the second attack were loaded with grain, witnesses told reporters.
No groups have yet claimed responsibility for the blasts, but it is believed the extremist Islamic militant group Boko Haram, who operate in the area, had planned the attack.
A Terminus Market official said he helped remove 50 casualties, most of them dead.
“It's horrifying, terrible,” said Mark Lipdo of the Stefanos Foundation, a charity based in Jos.
Mr Lipdo went on to claim that one of the blasts could have been prevented if the authorities had acted after on reports made by suspicious vendors, who saw that a white can had been parked for hours in the market place.
He said authorities were given a separate warning of impending violence: a man with explosives strapped to his body was arrested on Saturday and told police that many militants had been ordered to plant bombs around churches and public areas in Jos.
On Monday, a suspected suicide car bombing killed 25 people in Kano. Afterwards, police detonated a second car bomb in the northern city before it reached its target in the Christian quarter in the city.
President Goodluck Jonathan extended sympathies to affected families and “assure[d] all Nigerians that government remains fully committed to winning the war against terror, and this administration will not be cowed by the atrocities of enemies of human progress and civilization,” a statement said.
As a Christian from the south of the country, Jonathan has been accused of being indifferent to the fate of the predominantly Muslim north which has had to tolerate violent clashes with Islamic extremists Boko Haram for the past five years.
The group made international headlines in recent weeks, after it abducted 276 Nigerian schoolgirls whom it is threatening to sell into slavery if the government does not release detained Boko Haram militants.
The Nigerian government had previously rejected an offer to negotiate with Boko Haram, but said last week that it is prepared to commence talks, after it was accused of responding too slowly to the situation.
Britain, the US and France have supported the Nigerian government's search operation by sending military experts in surveillance, intelligence gathering and hostage negotiation to help re-unite the girls with their families.
On Tuesday, Nigeria asked a UN Security Council committee monitoring sanctions against al Qu’ida to add Boko Haram to the list, with an arms embargo and asset freeze, according to diplomats.