BAGHDAD — Partial results from Sunday's parliamentary elections showed Iraqi Prime Minister Nouri al Maliki ahead in two southern provinces but apparently trailing former Prime Minister Ayad Allawi in two central provinces, indicating a tight race amid allegations of fraud.

Only incomplete official figures were available as of late Thursday, covering about a third of the vote totals in five of Iraq's 18 provinces. No results were available yet for the main battleground: Baghdad.

Maliki's chief opponents disputed the tentative results and claimed widespread fraud in the ballot-counting process. Election officials said they were aware of only minor irregularities.

The complaints came from Maliki's two main challengers: the Iraqiya slate, anchored by Allawi, a secular Shiite Muslim with a large Sunni Muslim following who served as interim prime minister from 2004 to 2005; and the Iraqi National Alliance, an umbrella slate for Iranian-backed Shiite religious parties and the secular politician Ahmad Chalabi, a former U.S. ally.

As of Thursday evening, Maliki was ahead in two southern Shiite provinces — Babil and Najaf — where his strongest opponents came from the Shiite alliance, according to incomplete tallies released by Iraq's Independent High Electoral Commission, the body that's overseeing the elections. Maliki appeared to trail Allawi's secular, mixed-sect slate in the provinces of Diyala and Salahadin, which have large Sunni populations.

Results from a fifth province, Irbil, the capital of the mostly autonomous northern Kurdish region, showed that an alliance of the two main Kurdish parties was outpolling the breakaway reformist party Gorran.

Allawi and the Shiite alliance claimed fraud related to ballot gathering and counting and demanded that the early totals from each polling station be posted online to make sure the numbers jibe with the final count. "How can we be sure about the output when we don't know the input?" said Entifadh Qanbar, a senior Chalabi associate and a candidate with the Iraqi National Alliance.

At a news conference in Baghdad, members of Allawi's bloc showed a discarded ballot and photographs of ballot boxes that hadn't been taken to a central sorting station, suggesting that many votes weren't counted.

"We don't know how many papers were thrown out. Was it five or 5,000? That's why we're not confident about the results of these elections," Adnan al Janabi, a candidate on Allawi's slate, said at the news conference.

Hamdiya al Husseini, a senior official with the electoral commission, said in an interview with the state-owned Iraqiya channel that the results would be posted online. She added that there were some irregularities in the elections, but so far nothing serious enough to discredit the process.

No candidate is expected to win an outright majority, which means the coming weeks will see bargaining among the tickets and fierce jockeying to ally with the Kurds, whose support is crucial for coalition-building to form the next government and pick a prime minister.