Iranian troops crossed into Iraqi territory and seized an oil well that lies in a disputed area along the two countries' southern border, Iraq's deputy foreign minister said Friday.
The deputy minister, Mohammed Haj Mahmoud, said Iranian troops seized oil well No. 4 Thursday night in the al-Fakkah oil field, located in Maysan province about 200 miles southeast of Baghdad. The oil field is one of Iraq's largest.
Oil prices rose slightly after news of the incident.
The incursion by armed Iranians provided a dramatic display of the simmering border tensions between two nations, which have nonetheless grown close in recent years after a Shiite-led government rose to power in Iraq following the 2003 U.S.-led invasion.
Iraq's national security council held an emergency meeting late Friday to discuss the oil well takeover, and the government accused Iran of violating its sovereignty.
Government spokesman Ali al-Dabbagh said the seizure showed anew the need for clearly defined borders between Iraq and Iran.
"Iraq considers this penetration as a border breach and a violation of Iraq's sovereignty," al-Dabbagh said in a statement after the security council's meeting. "We call upon the Iranian government to solve all the border disputes with Iraq through diplomatic means and to avoid the use of military force."
Al-Dabbagh said Iraq and Iran have begun diplomatic talks as a result of the incursion.
Al-Dabbagh said the well takeover was carried out by a group of armed Iranians taking care to avoid the appearance of a military incursion. Earlier Friday, however, Iraq's deputy foreign minister confirmed in an Associated Press interview that it was Iranian soldiers who had seized the well.
"This is not the first time that the Iranians have tried to prevent Iraqis from investing in oil fields in border areas," Mahmoud told the AP.
CBS News correspondent Kimberly Dozier reports that an Army Press Agency Officer remarked, "It's kind of like 'capture the flag.' Every few months, one side seizes an oil well in the sketchily-marked area between the two countries. The other side protests. Foreign ministers exchange words. They retreat from oil well, and go back to square one."
The al-Fakkah field is considered a shared field between Iran and Iraq, meaning both nations are able to pump oil from it, but the Iraqis consider oil well No. 4 theirs. Iraq's state-owned Maysan oil company runs the field.
Iranian soldiers carrying rifles seized the well Thursday night in a 25-car convoy and ordered the Iraqi workers to leave the area, according to a worker at the site who did not want to be identified for fear of retribution. The soldiers then mounted an Iranian flag inside the well, he said.
There were no reports of violence during the incident, and Iranian forces left the well on Friday, leaving the flag behind, the worker said. His account could not be immediately confirmed by officials.
In Washington, a U.S. official said that although Iranians have crossed the border before, they had not previously ventured this far.
Iraqi security forces were in the area, but there are no reports of any fighting or any shots being fired, he said on condition of anonymity because he was not authorized to speak on the record. The Iranians are believed to have left the area, he said.
An official at the Iranian Embassy in Baghdad who did not want to be identified because he was not authorized to speak to news media told the AP that the reports of Iran seizing the oil well were "baseless and mere rumors."
A message left for Iran's Foreign Ministry spokesman seeking comment was not returned Friday evening.
Iran's semiofficial Mehr news agency quoted officials at the National Iranian Oil Company as denying reports that Iranian troops crossed the border.
Such incidents have happened before along the Iran-Iraq border, which was never clearly delineated after the brutal war between the two countries in the 1980s.
Last year, the Iraqi Oil Ministry accused Iran of stealing oil from the al-Fakkah field and of illegally seizing and capping off wells in a second field called Abu Gharb, which Iraq claims lies entirely within its territory.
The two adjacent oil fields both lie in Maysan province.
The deputy foreign minister said he did not know whether the Iranians were still in control of the oil well. The U.S. military in Iraq said it did not have any information on the incident.
Iraq has an estimated 115 billion barrels of proven oil reserves
the world's third largest, behind only Saudi Arabia and Iran.
But years of neglect, war and insurgency have left the oil fields performing far below what they're capable of. Iraq has been trying to attract international investment to develop its oil industry, including a round of international bidding last week that produced seven deals on the 15 fields offered.
The al-Fakkah field, which has about 1.55 billion barrels of oil in reserves, was offered along with another two adjacent fields as a single group in Iraq's first postwar oil and gas bidding round in June.
The group, which also included the Buzurgan and Abu Gharab fields, received only one bid by a consortium grouping China's CNOOC Ltd. and Sinochem International Co. Ltd. But their bid sought $21.4 from the government for each barrel produced and was rejected by the Oil Ministry, which wanted a price of $2.3 a barrel.
The three-field group's daily production ranges from 90,000 to 110,000 barrels per day.