"We will take necessary measures against those who committed these acts," Nechirvan Barzani said on a visit to the headquarters of the Islamic Kurdish Union, where supporters of his Kurdistan Democratic Party (KDP) allegedly fired guns and shouted slogans on Sunday evening.

He added that the gunfire had killed one person and injured a dozen others.

Police cordoned off the area surrounding the offices on Monday.

"I used to believe that our citizens had reached a point where they wouldn't do these things to express their joy," added Barzani, nephew of the region's president.

The Islamic Kurdish Union is a member of the leftist-Islamist Services and Reform list, which is expected to win as many as 17 seats in the 111-seat regional assembly, according to unofficial projections.

Services and Reform has complained of "fraud" and accused the region's two main parties of bussing unregistered voters to polling stations, claims that have been dismissed by Iraq's electoral commission.

The regional premier made no mention, however, of vandalism of three offices of the Goran (Change) list, which claimed to have won 28 seats in parliament.

The party's offices, all in the regional capital Arbil, were ransacked on Sunday -- allegedly by KDP supporters -- as unofficial results started to filter out.

"They entered three of our offices, broke everything and plastered the walls with photos of (regional president Massud) Barzani," said Goran official Othman Dachki, adding that assailants had also tried but failed to attack the Goran television station, Kurdistan News Network.

"We hold the (Kurdish) authorities responsible because they cannot guarantee competition between parties in a spirit of fair play," he said, adding there were no casualties.

Goran is run by Nusherwan Mustafa, a wealthy entrepreneur and former deputy leader of Iraqi President Jalal Talabani's Patriotic Union of Kurdistan (PUK).

Several members of the list are PUK defectors who quit the party just months before the elections to protest at what they claim is the PUK's unwillingness to reform and fight corruption.

Meanwhile, Hamdia al-Husseini, head of the electoral department at Iraq's electoral commission, said preliminary results would not be released Monday evening as previously announced because of counting delays in Sulaimaniyah and Dohuk provinces.

Nearly 80 percent of the region's 2.5 million voters took part in what poll officials trumpeted as a transparent election. Final results are not due for several days, as ballots must be transported to Baghdad for an official count.

A joint list uniting the KDP and PUK won 60 percent of votes cast in the parliamentary vote, presidential cabinet chief Fuad Hussein said Sunday.

He added that Massud Barzani won 70 percent of the vote in a simultaneous presidential poll pitting him against four other candidates.

The two parties have dominated Iraqi Kurdish politics for half a century, first as rebels and then as the region's effective rulers in the aftermath of the 1991 Gulf war over Saddam Hussein's invasion of neighbouring Kuwait.

The results would give the KDP-PUK list around 55 seats in the 111-seat parliament, down from 78 seats in the outgoing assembly elected in 2005.

The vote was held at a key time in Iraq's transition as regional leaders are locked in a bitter dispute with Baghdad over land and oil, while local voters also voiced increasing concern over corruption.