BAGHDAD - Former U.S.-backed prime minister Ayad Allawi and his secular, anti-Iranian coalition narrowly won Iraq's parliamentary elections in final returns Friday, edging out the bloc of Prime Minister Nouri al-Maliki, who angrily vowed to challenge the results.

If Allawi's coalition remains on top, it will get the first opportunity to form a parliamentary majority and Iraq's next government, and complete his emergence from what once appeared to be the political graveyard. But they do not automatically mean that he will become prime minister, and the narrow margin sets the stage for months of political wrangling.

A coalition including anti-American cleric Muqtada al-Sadr finished a strong third and could end up playing the role of kingmaker. Kurdish parties also could be crucial in determining who will rule the oil-rich Arab nation of 28 million people.

Allawi told cheering supporters at his Baghdad headquarters he wants to help build a stable region that would help "achieve prosperity for (Iraq's) people."

"On this occasion, I'd like to congratulate the Iraqi people and extend the hand of friendship to all neighboring and world countries," said Allawi, a secular Shiite politician who appealed across sectarian lines to minority Sunnis who have been out of power since the downfall of Saddam Hussein.

Baghdad's Sunni neighborhoods, the site of vicious sectarian fighting just a few years ago, erupted in cheering, honking of horns and celebratory gunfire in support of the man they have endorsed as their own.

"Today is a historic and joyful day which will witness a change for the sake of Iraqi people," said Hameed Marouf, an Allawi supporter in Azamiyah.

But the results released Friday portend an ugly, protracted battle. No coalition is close to the 163 seats needed to control the 325-seat parliament.

Allawi's Iraqiya coalition won 91 seats to 89 for al-Maliki's State of Law bloc. The Iraqi National Alliance, a Shiite religious group dominated by al-Sadr's followers, won about 70 seats, and Kurdish parties picked up 51.

Regardless of who eventually comes out on top, the results of the March 7 elections suggest that millions of Iraqis are fed up with a political system that revolves around membership in one of the two major Islamic sects.

Iraqiya's win also shows that many Iraqis are suspicious of Iranian influence. Allawi was widely seen as closer to the region's Arab governments than to neighboring Shiite Iran.