Iraqi officials nullified election results in more than 30 polling stations due to fraud in last month's provincial balloting, but the cases were not significant enough to require a new vote in any province, the election chief said Sunday.

Faraj al-Haidari said final results of the Jan. 31 voting would be certified and announced this week.

Preliminary official results announced Feb. 5 showed Prime Minister Nouri al-Maliki's ticket swept to victory over Shiite religious parties in Baghdad and southern Iraq — a strong endorsement of his crackdown on Shiite extremists.

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Voters in 14 of the 18 provinces were choosing members of ruling provincial councils in an election seen as a dress rehearsal for parliamentary voting by the end of the year.

Al-Haidari said his commission had looked into fraud allegations from across the country and would announce the findings along with the certified results. But he added "we won't cancel" the election in any province.

He told The Associated Press that the polling stations where ballots were nullified were scattered in all 14 provinces, but he refused to say where the largest number was found. He did not say how many ballots were affected.

One official, who spoke on condition of anonymity because he was not supposed to talk about the vote to media, said the most widespread fraud appeared to have been in Diyala province, which has large Sunni, Shiite and Kurdish communities and an ongoing insurgency.

A coalition including the Iraqi Islamic Party, the largest Sunni political group, led in Diyala with 21.1 percent of the vote followed by a Kurdish alliance with 17.2 percent, according to preliminary results.

Al-Maliki's coalition finished fourth in Diyala with 9.5 percent.

U.S. officials have been closely watching the Diyala results for signs of friction between Arabs and Kurds, who are the biggest community in the far north of the province.

The Kurds were hoping that a strong Kurdish showing in those areas would bolster their case for incorporating the territory into the Kurds self-ruled region.

Also Sunday, a bomb hidden in a garbage pile killed one person and injured 18 others in Sadr City, the Baghdad Shiite neighborhood that had been a Shiite militia stronghold until the Iraqi army took over the area last spring.

A roadside bomb in another predominantly Shiite Baghdad neighborhood, Talibiyah, missed a passing police patrol Sunday and injured three civilians, said a police official, speaking on condition of anonymity because he was not authorized to talk to media.

Sunni militants have kept up their attacks against Shiites, hoping to re-ignite the kind of sectarian conflict that engulfed the country two years ago. A series of bombings against Shiite pilgrims heading to the holy city of Karbala killed 60 people and wounded 170 last week.

In response, the Iraqi government stepped up security, adding 5,000 plainclothes military personnel to the more than 30,000 already deployed to protect Shiite pilgrims on their way to Karbala, 50 miles south of Baghdad.

Police arrested a would-be suicide bomber south of Baghdad on Sunday who had explosives under his clothes and said he was planning to target pilgrims headed to Karbala, said a police official, speaking on condition of anonymity because he was not authorized to talk to the media.

The pilgrims are headed to Karbala to celebrate Monday's end of 40 days of mourning that follow the anniversary of the seventh-century death of the Prophet Muhammad's grandson Hussein, one of Shiite Islam's most revered saints.

He was killed near Karbala in a battle for the leadership of the Muslim nation following Muhammad's death in 632. His death enshrined the split between Sunni and Shiite Muslims.