There is uncertainty over the final death toll in Tuesday's devastating multiple bomb attacks in northern Iraq against the minority Yazidi community.
Rescuers are having to scour through the rubble by hand
The interior ministry said at least 400 people had died. But police officials and the health ministry dispute this, saying more than 200 were killed.
Earlier, the regional governor said as many as 200 people may still be buried.
The bombing of two Yazidi villages near Mosul was one of the worst attacks in more than four years of war in Iraq.
It has already surpassed the killing of just over 200 people in car bombings and mortar fire in Baghdad's Shia stronghold of Sadr City last November.
An Iraqi health ministry official told the BBC that he was unable to confirm the 400 figure following his visit to the scene.
In the latest violence, a bomb attack in a central square in the capital was reported to have killed at least seven people.
The US military also announced that two soldiers were killed and six injured in fighting north of Baghdad on Wednesday.
The US military blamed al-Qaeda for the Yazidi bombings, saying it fitted the profile of "spectacular" strikes expected by al-Qaeda during the ongoing US "surge" operation.
Correspondents say the Americans fear insurgents are moving into new areas where they can attack so-called soft targets.
The US commander in Iraq, Gen David Petraeus, will issue a report into the progress of the surge in September.
Iraq's Prime Minister Nouri Maliki, a Shia, and President Jalal Talabani, a Kurd, also added their condemnation.
The co-ordinated bombings in the villages of Qataniya and Adnaniya involved a fuel tanker and three cars, officials said.
The force of the blasts ripped apart houses, many of which were made of no more than clay and mud.
'Hands and shovels'
The governor of Tal Afar told the BBC the current toll of 250 dead and 350 injured was expected to rise sharply, adding that as many as 200 people could still be buried under the rubble.
Poor families in the Yazidi community often crowd as many as 30 people in one home, he said.
The mayor of Sinjal, another nearby town, said on Wednesday that he expected the final death toll to rise.
KEY FACTS: THE YAZIDIS
Religious sect found in northern Iraq, Syria and the Caucasus
Number about 500,000 worldwide, but largest number in northern Iraq
Doctrine is an amalgam of pagan, Sabean, Shamanistic, Manichean, Zoroastrian, Jewish, Christian and Islamic elements
Yazidis believe in a Supreme God, but do not believe in evil, sin, hell or the devil
Violation of divine laws can be expiated by metempsychosis, or the transferring of a soul from one body to another
Principal divine figure, Malak Taus (Peacock Angel), is the supreme angel of the seven angels who ruled the universe after it was created by God
"We are still digging with our hands and shovels because we can't use cranes as many of the houses were built of clay," Dhakil Qassim told AP.
A spokesman for the Kurdistan regional government, a semi-autonomous authority which governs three northern Iraqi provinces, described the Yazidi as a "threatened minority" and said Kurdish forces might have protected them from harm.
"But because of the inaction of the government in Baghdad and their inability to protect the population they are suffering the way they are now," he added.
Tensions between the Yazidi sect and local Muslims have grown since a Yazidi girl was reportedly stoned by her community in April for converting to Islam.
The sect is due to vote later alongside other Kurds outside the Kurdish autonomous region in a referendum on joining the grouping.
Correspondents say the planned referendum makes northern Iraq's Kurds a target for politically-motivated attacks.
Yazidis worship an archangel, sometimes represented by a peacock figure, believed by some Christians and Muslims to be the devil.