Saturday's attack targeted pilgrims returning from a religious ceremony at the al-Askari mosque in the former insurgent stronghold of Samarra, north of Baghdad. The violence highlighted renewed efforts this year by insurgents to incite sectarian violence after a lull in attacks.
Police and hospital officials said 64 people were wounded in the suicide bombing that came after ceremonies there marking the death of a revered ninth century religious figure buried there.
Al-Askari mosque in Samarra, 60 miles (95 kilometers) north of Baghdad, has been a flashpoint for bloodshed in the past. A 2006 bombing by Sunni insurgents destroyed its golden dome and sparked retaliatory attacks between Sunnis and Shiites that brought the country to the brink of civil war.
No group has yet claimed responsibility for the most recent suicide bombing, which bares the hallmarks of al-Qaida or its allied Sunni-dominated militant organizations who consider Shiites as heretics and enemies.
The officials did not want to be identified because they were not authorized to speak to the media.
In the northern city of Mosul, an Iraqi man died after pouring gasoline on himself and setting himself on fire late Saturday, Iraqi officials and relatives said.
The death of Abdul Amir Majeed, a 31-year-old laborer, mimicked the suicide of a young Tunisian man who set himself on fire to protest a lack of jobs and harassment by authorities. His death tipped off widespread protests across the country that eventually toppled the Tunisian government and led to a string of copycat self-immolations in the Arab world.
Majeed's father, Abdullah, said his son suffered unemployment and poverty: "We lost him because of the pressures of life." Police and hospital officials speaking on condition of anonymity because they were not authorized to speak to the media confirmed the death.
Since the death of the Tunisian man, a number of people throughout the Middle East have set themselves on fire, though only a few have died.
Iraq, which is home to one of the few democracies in the Middle East, has not seen anything near the widespread protests that have buffeted Egypt, Yemen or Tunisia.
But in small-scale gatherings across the country, protesters have called for improved government services and security. More than 200 people rallied in the southern city of Nasiriyah, about 200 miles (320 kilometers) southeast of Baghdad Sunday to protest the lack of government services such as electricity, said a police official there.
In Ramadi, 70 miles (115 kilometers) west of Baghdad, about 300 people marched, also to demand better government services, a city police officer said. Both officials did not want to be identified because they were not authorized to speak to the media.
In Baghdad, the Iraqi parliament endorsed eight new ministers as part of Prime Minister Nouri al-Maliki's government, but still left the key security posts unfilled.
On Dec. 21, al-Maliki presented a partial Cabinet to parliament as part of his new government which ended nine months of political wrangling following the inconclusive March 7 elections. But many of the posts were filled with acting ministers, reflecting the difficulties forming a consensus in al-Maliki's fragile coalition government.
On Sunday, lawmakers approved new ministers of trade, municipality and electricity, as well as five other ministers. Al-Maliki promised to present candidates for the security posts - defense, interior and national security - soon.
"I'd like to assure you that the candidates for the security ministries will take only a few days," al-Maliki told lawmakers without giving a specific date.
Iraq's government has a total of 44 Cabinet ministers.
Associated Press writer Mazin Yahya contributed to this report.