Baghdad residents held funerals Saturday for victims of a suicide bombing that killed 28 people in a city park, even as authorities pressed operations against militants to stem growing violence.

Authorities have launched a fierce crackdown on militants blamed for a wave of nationwide shootings and blasts that has killed more than 3,600 people this year, but have faced criticism for not addressing the root causes of the violence.

Prime Minister Nuri al-Maliki has nevertheless vowed to press on with the campaign, even as analysts and diplomats have voiced fears that Iraq is teetering on the edge of a return to the all-out sectarian war that left tens of thousands dead in 2006 and 2007.

Friday's violence killed 37 people, most of them in Baghdad.

In the worst attack, a suicide bomber detonated explosives in a small park in the confessionally-mixed north Baghdad neighbourhood of Qahira, where families were gathered in the evening.

The blast -- like many recent ones targeting crowded areas to inflict maximum casualties -- killed at least 28 people and wounded 58 others, security and medical officials said.

"This morning, there was a funeral for 30 people and many, many others were wounded, and most of them will die because nobody cares about them," said one of the mourners, Sharif Mohammed.

He slammed what he said was apathy among politicians and said: "Isn't this bloodshed enough for them?"

Nine other attacks in Baghdad, Mosul, Dujail and Hilla killed nine people on Friday.

On Friday Maliki issued two statements on violence in Lebanon and Syria but made no mention of the unrest plaguing Iraq.

The violence came as authorities announced the latest in a series of operations launched following brazen assaults on prisons near Baghdad last month, claimed by an Al-Qaeda front group, that officials say enabled hundreds of prisoners to flee, including several senior militants.

Security forces arrested seven militants in north Iraq, a statement from a joint army-police command centre said, including the self-styled minister of finance of the Islamic State of Iraq and the Levant, an Al-Qaeda front group.

In recent weeks, officials have said they dismantled many militant training camps and bomb-making sites.

Maliki, who has vowed to pursue suspects across Iraq, said in a recent speech that dozens of militants were killed and more than 800 alleged militants arrested as a result of the operations.

But analysts and diplomats say authorities have failed to address the root of the problem -- namely anger among Iraq's Sunni Arab minority over their alleged ill-treatment at the hands of the Shiite-led government.

Unrest has surged in Iraq this year to levels not seen since 2008, when the country was emerging from a brutal Sunni-Shiite sectarian conflict that claimed tens of thousands of lives.

Attacks have killed more than 3,600 people since the beginning of 2013, according to figures compiled.

In addition to major security problems, the government in Baghdad has also failed to provide adequate basic services such as electricity and clean water, and corruption is widespread.

And political squabbling has paralysed the government, which has passed almost no major legislation in years.