A spate of bombings targeting Shiite Muslims across Iraq killed 22 people on Thursday, the latest in a spike in unrest amid weeks of anti-government protests and a political crisis engulfing the country.

The attacks marked the third consecutive day of violence which has claimed 81 lives overall, including that of a Sunni Iraqi MP killed by a suicide bomber and 33 others who died in twin car bombs in an ethnically mixed northern city.

It comes as Iraq grapples with a long-running political dispute, with Prime Minister Nuri al-Maliki facing protests hardening opposition against his rule and calls from many of his erstwhile government partners for his ouster.

No group has claimed responsibility for the latest bombings, but Sunni militants often launch attacks in a bid to destabilise the government and push Iraq back towards the sectarian violence that blighted it from 2005 to 2008.

The bloodiest of Thursday's blasts took place in Dujail, 60 kilometres (35 miles) north of Baghdad, where a car bomb outside a Shiite mosque killed nine people and wounded 56 others, said town mayor Mohammed Hassan.

A car bomb killed seven other people and wounded 17 near a football stadium on the outskirts of the predominantly Shiite city of Hilla, south of the capital, officials said.

Witnesses reported residents throwing stones at a police officer after he blamed locals for helping militants carry out the bombing. Police in the town where the attack took place said the officer was later detained.

Bombings also struck Baghdad, Hawija and Karbala, while two soldiers and two policemen were killed in separate shootings near the northern cities of Mosul and Tuz Khurmatu.

There were no casualties in Hawija but two people were killed and one wounded in a roadside bomb in north Baghdad.

And in Karbala, a Shiite shrine city south of the capital, 17 people were wounded, including eight Afghan Shiite pilgrims, in a morning blast, followed by two explosions in the evening that left at least seven more injured.

Afghan ambassador to Baghdad Mohammed Anwarzai confirmed to AFP that a number of his compatriots were wounded in the morning blast.

The violence comes a day after 49 people were killed in attacks in Baghdad and north of the capital -- Iraq's bloodiest day since November 29 -- including seven who died from twin car bombs in the city of Kirkuk.

On Tuesday, a suicide attacker killed a Sunni Iraqi MP, Ayfan al-Essawi, west of Baghdad. Hundreds of mourners attended Essawi's funeral outside the mostly Sunni town of Fallujah on Wednesday.

The lawmaker was a former leader of the Sahwa -- Sunni tribal militias who turned against Al-Qaeda and sided with the US military from late 2006, helping to turn the tide of Iraq's bloody insurgency.

Sahwa fighters are frequently targeted for attacks by Sunni militants who view them as traitors.

The violence comes amid a political crisis that has pitted Maliki against several of his ministers just months ahead of key provincial elections.

Weeks of anti-government demonstrations in Sunni Arab majority areas, supported by several parties that are members of Maliki's unity cabinet, have hardened opposition against the premier, a Shiite.

The violence and political disputes come with barely three months to go before provincial elections, Iraq's first polls in three years and a key barometer to gauge the popularity of Maliki and his rivals.

Attacks in Iraq are down from their peak in 2006-2007, but they are still common across the country.