A series of attacks in Baghdad and north Iraq killed 48 people on Sunday amid a surge in violence that authorities have failed to stem despite wide-ranging operations targeting militants.

Prime Minister Nuri al-Maliki has vowed to press on with his anti-insurgency campaign, which has reportedly led to the arrest of hundreds of alleged militants and the killing of dozens.

But analysts and diplomats say authorities have failed to tackle the root causes of Iraq's worst violence since 2008: anger in the Sunni Arab community over perceived ill-treatment by the Shiite-led authorities and security forces.

Sunday's violence, which left more than 100 people wounded, struck the Baghdad area and predominantly Sunni Arab towns and cities to the north, but the deadliest of the attacks hit the capital.

A series of bombings -- two car bombings and a roadside bomb -- went off between 4:00 pm (1300 GMT) and 5:30 pm (1430 GMT) in Baghdad and its outskirts, killing nine people and wounding 22 others, officials said.

The blasts struck a variety of neighbourhoods across the city, and were the latest in a burgeoning trend of militant attacks in the afternoon and evening in Baghdad.

In previous years, deadly attacks have typically struck during the morning rush-hour when much of the capital is in gridlock.

Along with the spate of blasts, two other bombings in Baghdad killed nine and wounded 29.

Attacks also struck Diyala, Salaheddin and Nineveh provinces to the north of the capital.

The worst hit the confessionally-mixed city of Baquba, capital of Diyala, where 17 people were killed in all.

A car bomb in a market area on the western outskirts of the city killed 11 people and wounded 34 others, while a bombing at a Shiite Muslim wedding in central Baquba killed five people and wounded eight others.

Earlier, explosions against the home of a recently-returned family that had been displaced within Iraq killed a child and wounded nine other members of the family.

In Salaheddin, a car bomb near the town of Balad killed five people and wounded 21 others, among them a senior judge who was the apparent target of the blast.

In restive Nineveh province, gunmen opened fire on a van ferrying soldiers from Baghdad to their unit in the provincial capital Mosul, killing five of them.

Also in Nineveh, three separate attacks by gunmen left a soldier and two civilians dead, including a member of the Shabak minority.

The 30,000-strong Shabak community mostly lives near Iraq's border with Turkey.

They speak a distinct language and largely follow a faith that is a blend of Shiite Islam and local beliefs. Shabaks are frequently targeted in attacks by militants.

Violence has markedly increased in Iraq this year.

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

The surge in violence has raised concerns that Iraq is teetering on the brink of a return to the all-out sectarian war in 2006-2008 that left tens of thousands dead.