The Goran (Change) list said it had won more than a quarter of seats in the regional Kurdish parliament in Saturday's legislative election, raising the prospect of a strong opposition for the first time.

Incumbent regional president Massud Barzani won 70 percent of the vote in a simultaneous presidential poll pitting him against four other candidates, presidential cabinet chief Fuad Hussein said on Sunday.

But in a sign of tensions, three Goran offices in the regional capital of Arbil were ransacked by Barzani supporters on Sunday after unofficial results started to filter out, while another party has complained of vote fraud.

"They entered three of our offices, broke everything and plastered the walls with photos of 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.

A joint list uniting Barzani's Kurdistan Democratic Party (KDP) and the Patriotic Union of Kurdistan (PUK) of Iraqi President Jalal Talabani won 60 percent of ballots cast in the parliamentary vote, Hussein said.

The KDP and PUK 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.

A senior Goran official told AFP his party would win 28 seats, making it the first credible opposition to the longstanding KDP-PUK grip in the rugged mountainous north of Iraq.

The list is run by Nusherwan Mustafa, a wealthy entrepreneur and former PUK deputy leader. Several members of Goran 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.

A leftist-Islamist list also complained of "fraud" and accused the PUK and KDP of bussing unregistered voters to polling stations, claims that have been dismissed by Iraq's electoral commission.

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.

"We hope these elections will be a first step to solving issues with Baghdad," Barzani said.

But the Kurdish regional president also insisted he would "work to get back the disputed areas," referring to longstanding Kurdish demands to incorporate the oil province of Kirkuk and historically Kurdish-majority parts of three other provinces into their autonomous region.

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.

The UN's Iraq offices congratulated Kurds for "having turned out in large numbers, especially among women ... in an orderly environment, notably free of violence" and implored people to "show patience until the publication of the final results."

Iraqi Prime Minister Nuri al-Maliki described the polls -- held six months after the rest of the country voted in provincial elections -- as "another step in building a democratic Iraq."