FACTBOX: Iraq's disputed city of Kirkuk

(Reuters) - Iraq's government may be dreaming of the vast wealth it plans to extract from oilfields around Kirkuk, but residents of the restive city have different appraisal of a resource they say has brought them nothing but trouble.

The following are some facts about the northern city of Kirkuk and its surrounding province:

* THE CITY:

Kirkuk, 250 km (155 miles) north of Baghdad, is the capital of Tamim province, which is also known as Kirkuk province.

Kirkuk sits atop one of Iraq's key oil producing fields. The Kirkuk fields contain about 13 percent of Iraq's proven reserves, which in turn are the world's third largest. U.S. officials believe the province could contain 4 percent of the world's oil reserves.

Kirkuk city is one of Iraq's biggest urban areas. It lies just outside the largely autonomous Kurdistan region, which is predominantly Kurdish.

* THE PEOPLE:

Kurds, Arabs and Turkmen make up Kirkuk's three main ethnic groups. The city is also home to Chaldean Christians and other minorities. Thousands of Arab families moved to Kirkuk in the 1970s and 1980s under Saddam Hussein's "Arabisation" policy, which involved the expulsion of thousands of Kurds and Turkmen.

The size of each ethnic group in Kirkuk is disputed, making population statistics unreliable. Arabs and Turkmen say hundreds of thousands of Kurds have settled in the city since the 2003 U.S.-led invasion.

* THE HEART OF THE DISPUTE:

Kurds consider Kirkuk their ancient capital and want to make it part of their northern region. Arabs and Turkmen want the city to remain under central government authority. Arabs and Turkmen believe Kirkuk has been intentionally stacked with Kurds to tip the demographic balance in their favor in any ballot.

Kurdish ambitions cause concerns in neighboring Turkey, which faces separatism among its own sizable Kurdish population.

* ELECTIONS:

Kirkuk was excluded from provincial elections in January 2009 because no one could agree on how to hold the vote there.

* THE UNITED NATIONS:

The United Nations has called Kirkuk the "mother of all issues" in the country and says a peaceful solution to the dispute is vital to Iraq's stability. A U.N. report released to the Iraqi government in April, which contains four options for the region, is supposed to provide an objective basis for a discussion of the future of Kirkuk. The United Nations does not endorse any single option.

* WHAT ABOUT A REFERENDUM?

A referendum mandated by the constitution was to have been held by the end of 2007 to decide Kirkuk's status. It was delayed, partly to give the United Nations time to come up with its proposals. There is no referendum currently planned.

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(Editing by Sophie Hares)