The United Nations has handed the Iraqi government a report it hopes will help end decades of deadlock over Kirkuk, an ethnically mixed region that sits on as much as 4 percent of the world's oil supply.

Staffan de Mistura, who heads the UN mission in Iraq, presented the report to Iraqi President Jalal Talabani, Prime Minister Nuri al-Maliki, and Iraqi Kurdish President Massoud Barzani, the United Nations said in a statement.

The report, a year in the making, contains four options to overcome disputes over control of Kirkuk and recommendations on 14 other contested areas in northern Iraq. The options, all of which treat the province as a single unit, were not made public.

"We are all too aware that tensions have recently risen in parts of the disputed areas ... We are hoping that sustained and serious dialogue will now follow," de Mistura said.

A UN official, who asked to go unnamed, said that de Mistura had already briefed Talabani, Maliki, and Barzani and that their initial response had been "broadly positive."    

The report comes as tensions run high in Kirkuk, where Arabs and minority Turkmen and Kurds view one another suspiciously after decades of bloodshed, political manoeuvering and hardship.

Saddam Hussein, a Sunni Arab ousted by the US-led invasion of Iraq in 2003, moved Arabs to the city en masse in order to dilute Kurdish influence there. After Kurds gained control of the provincial government in 2003, Kurds have flooded back.

Kurds insist that Kirkuk is a rightful part of their largely autonomous northern region, an idea rejected by Turkmen and Arab leaders who fear becoming second-class citizens.

As violence between once-dominant Sunni and majority Shi'ite Arabs subsides, many fear the greatest threat to Iraq's stability now lies along the "green line" demarcating Kurdistan.

Tensions have increased in Kirkuk, where 10 people died in a bomb attack last week, as Maliki takes steps to boost the Iraqi Army's presence there, alarming Kurdish Peshmerga troops.

The US military made a sudden decision to more than double its troop presence in Kirkuk earlier this year. Soldiers there now focus on brokering communication between rival groups.

Across Iraq, there are fears violence will surge anew as political and armed groups position themselves ahead of national elections expected late this year. The elections will only make it more difficult to find consensus on Kirkuk, officials say.

Each option put forward by the United Nations would require a political agreement -- a monumental task -- followed by a confirmatory referendum.

"If we thought we were going to inflame the situation still further by doing so, we wouldn't have submitted these reports," the UN official said.

Following the report's submission to the Iraqi government, stakeholders will be able to contest points they see as factually incorrect. After that, the United Nations hopes that senior officials will sit down and discuss the options.

"We are not pushing to have a role in dialogue, but we stand ready to help if asked by the parties," the UN official said. "We believe this it is the right time to start dialogue." - Reuters