Seven bombs ripped through Baghdad killing seven people Thursday, hours after American lawmakers criticised the slow pace of political reconciliation in Iraq which they said was stoking the worsening violence.

The blasts, which mostly targeted Shiite-majority neighbourhoods of the capital, come amid the country's deadliest protracted period of unrest since 2008 as security forces grapple with near-daily attacks and battle militants in Anbar province.

Diplomats have called for the Shiite-led government to do more to reach out to the disaffected Sunni Arab minority, but with a general election looming in April, Prime Minister Nuri al-Maliki has taken a hard line.

There has been no let-up in the bloodshed, with seven bombs going off across Baghdad from around noon (0900 GMT), while militants also mounted a massive, though ultimately abortive, assault on a jail in northern Iraq.

The blasts in the capital killed at least seven people and wounded more than 40, security and medical officials said.

Four of the neighbourhoods hit are populated mostly by Iraq's Shiite majority. The other three bombs went off in commercial districts in the centre of Baghdad.

The blasts came a day after 33 people were killed in the capital, 25 of them in a series of bombings near the heavily fortified Green Zone, which is home to parliament, the prime minister's office and the US and British embassies.

No one immediately claimed responsibility for the latest attacks, but Sunni militant groups, including the jihadist Islamic State of Iraq and the Levant (ISIL), have claimed previous bombing campaigns targeting Shiites in the capital.

Elsewhere in Iraq on Thursday, a car bomb near a Kurdish political party's offices killed one person in Tuz Khurmatu, while a police general and his bodyguard were wounded by a bombing in Baquba.

In Nineveh province in the north, militants mounted a massive assault on Badush prison late on Wednesday, reminiscent of twin attacks on jails near Baghdad last July that succeeded in freeing dozens of inmates.

The attempted prison break left one guard dead and 14 wounded, and involved mortar fire as a riot broke out inside the jail, but was ultimately repulsed, the justice ministry said.

Maliki 'may not be up to it'

US House Foreign Affairs Committee chairman Ed Royce said on Wednesday that Maliki's failure to do more to address Sunni grievances had allowed ISIL to exploit the minority community's "alienation" to sharply step up its attacks.

"As head of state, while he may not be up to it, Maliki must take steps to lead Iraq to a post-sectarian era," Royce said.

"Al-Qaeda has become very skilled at exploiting this sectarian rift, and Maliki's power grab has given them much ammunition."

US Deputy Assistant Secretary of State for Iraq and Iran Brett McGurk insisted Maliki had made changes since he visited Washington in November and "got a very direct message" from President Barack Obama on "enlisting the Sunnis into the fight".

ISIL has also been fighting security forces in Anbar, a mostly Sunni desert region bordering Syria where militants have held parts of Ramadi and all of Fallujah for weeks.

Security forces and tribal auxiliaries have made slow progress in Ramadi but recaptured several neighbourhoods late Tuesday, an AFP journalist reported.

In Fallujah, however, security forces have largely stayed out of the city for fear that major incursions could spark high civilian casualties and heavy damage to property.

The city was a bastion of the Sunni insurgency following the 2003 US-led invasion, and American troops there fought some of the costliest battles since the Vietnam War.

Ahmed Abu Risha, a prominent tribal leader in the Sunni Awakening movement, which allied with US troops against Al-Qaeda and now supports the government, said an attack on the city was imminent and has urged anti-government fighters to lay down their arms.

The standoff in Anbar has prompted more than 140,000 people to flee their homes, the UN refugee agency said, describing it as the worst displacement in Iraq since the peak of sectarian fighting between 2006 and 2008.