The United States on Tuesday warned US firms including oil giant ExxonMobil, which has signed a contract with Iraqi Kurdistan against Baghdad's wishes, of the legal risks of such deals.

"The United States has advised all of our companies, including ExxonMobil... that they run significant political and legal risks if they sign contracts with any parties in Iraq before there has been a national agreement," on how to distribute oil revenue, State Department spokeswoman Victoria Nuland said.

Last week, an Iraqi oil ministry official said Baghdad was studying its options with respect to ExxonMobil, which last month signed a deal with Kurdistan to explore six areas.

The Iraqi oil ministry official said two of those areas -- Al-Qosh and Bardarash -- are actually parts of Nineveh province that Kurdistan wants to annex into its autonomous region, a move Baghdad opposes.

Baghdad regards any contracts not signed with the central government as invalid. In the past, Iraq has banned oil companies that have signed contracts in Kurdistan from taking part in tenders or contracts for other fields.

"For many years, in fact, the United States has been urging all parties in Iraq to enact the necessary national laws that can govern the oil and gas sector," Nuland said.

"The sooner they do that, the sooner companies can -- can invest in a legally viable way."

Turkey bombs Iraq, wounds civilian: officials
Sulaimaniyah, Iraq (AFP) Nov 23, 2011 - Turkey has bombed the Sulaimaniyah and Arbil provinces of Iraq's autonomous northern Kurdish region, wounding one civilian, Kurdish officials said on Wednesday.

"The Turkish aerial bombardment was renewed on Tuesday night and the civilian Ismail Baz Hamed, 20, was wounded during this bombing," said Hassan Abdullah, the mayor of the Qalat Dizah area in Sulaimaniyah.

"The bombing caused heavy damage to farms and livestock in Qalat Dizah," he said.

An official from Kurdistan region's interior ministry said there were also strikes in Arbil province.

"Turkish airplanes bombed many areas... in Arbil on Tuesday night," the official said on condition of anonymity.

It was the second time Turkey has reportedly carried out strikes in Kurdistan this month, as part of its long-running conflict with the separatist Kurdistan Workers' Party (PKK), which has bases in the region.

The Turkish military launched an operation in Kurdistan last month after a PKK attack killed 24 soldiers in the town of Cukurca near the Iraqi border, the army's biggest loss since 1993.

Listed as a terrorist organisation by Turkey and much of the international community, the PKK took up arms for Kurdish independence in southeastern Turkey in 1984, sparking a conflict that has killed about 45,000 people.