Goodluck Jonathan, Nigeria's president, promised immediate action to find the men who ordered multiple blasts on Friday night in Kano, northern Nigeria's main city.
Morgues were full and bodies were being stored in corridors on Sunday morning as emergency services continued to find fresh victims of the blasts.
One hospital official said at least 178 people were killed in the attack. That death toll could rise to as high as 250, another doctor in Kano said, because many bodies had been taken to other hospitals and outlying clinics.
Boko Haram on Saturday said it carried out the attacks. The Islamist separatists appear to have changed tactics in recent months to a policy of ethnically cleansing Christians from northern Nigeria.
President Jonathan said Boko Haram would "face the full wrath of the law".
However, his government has repeatedly been unable to stop attacks by the group, and last week admitted that the chief suspect in the Islamists' Christmas Day attacks on a church had escaped from police custody.
Police stations, immigration offices, government buildings and the headquarters of Nigeria's secret police were among the targets struck on Friday night.
There are concerns that Boko Haram may aim to provoke a civil war in Nigeria, with the intention of splitting the majority Muslim north away from the Christian south.
"They are creating a lot of noise, and are employing some terrifying tactics, but I don't think we can say yet that they have the support truly to pull the country in two," said one Western diplomat in Abuja, the Nigerian capital.
The Foreign Office warned British visitors to cancel trips to Kano and for those already there to "exercise vigilance" and comply with state-ordered curfews.
A 24-hour movement ban imposed on Saturday had been eased to one from dusk to dawn on Sunday.