One of the deadliest bombings to ever hit Iraq killed 323 people, two thirds of whom needed DNA testing to identify, the health minister said, raising an earlier toll from last month's attack.

A suicide bomber detonated an explosives-rigged minibus in a crowded shopping area in Baghdad's Karrada district early on July 3, sparking infernos in nearby buildings that burned many victims alive.

"One hundred and fifteen martyrs were identified directly after the bombing by their families," health minister Adila Hamoud told a televised news conference.

But the identity of 208 more people killed in the blast, many of whose bodies were burned beyond recognition, could not be determined, and they were sent for DNA testing, Hamoud said.

She had previously said that the attack, which was claimed by the Islamic State jihadist group, had killed 292 people, of whom 177 were unidentified.

People have been furious over delays in determining the fate of their loved ones, and have sharply criticised the Iraqi government for failing to protect them.

IS overran large areas north and west of Baghdad in 2014, but Iraqi forces have since regained significant territory from the jihadists.

The extremists have responded to battlefield setbacks by striking back against civilians, and experts have warned there may be more bombings as the jihadists continue to lose ground.

UN slams Iraq PM's efforts to accelerate executions
Baghdad (AFP) Aug 1, 2016 - Given problems with Iraq's judicial system, the premier's efforts to speed up the implementation of executions will only "accelerate injustice", the United Nations said on Monday.

Prime Minister Haider al-Abadi last month ordered the formation of a committee to identify factors that are delaying the implementation of the death penalty and to make recommendations on how to speed up the process.

"Given the weaknesses of the Iraqi justice system, and the current environment in Iraq, I am gravely concerned that innocent people have been and may continue to be convicted and executed," UN High Commissioner for Human Rights Zeid Ra'ad Al Hussein said in a statement.

"Fast-tracking executions will only accelerate injustice," Zeid said.

UN monitoring "has revealed a consistent failure to respect due process and fair trial standards, including a reliance on torture to extract confessions", according to the statement.

Iraq has for years faced widespread criticism from diplomats, analysts and human rights groups who have said that, due to a flawed justice system, those being executed are not necessarily guilty of the crimes for which they were sentenced to die.

Following a bombing in Baghdad that killed more than 320 people earlier this month, the justice ministry announced that five people had been put to death in a statement linking the timing of the executions with the blast.

Zeid said that, with Iraqis facing frequent attacks, including by the Islamic State jihadist group, "it becomes all too easy to permit such atrocities to stoke the fires of vengeance".

"But vengeance is not justice," he said.