Kurdish leaders are angry that American and British officials turned down their request to have a reference to the interim constitution, which enshrines Kurdish federalism, included in the U.N. resolution approved Tuesday.
The Iraqi Shiite leader Grand Ayatollah Ali al-Sistani rejected any mention of the interim charter in the resolution. Shiites oppose parts of the charter that grant Kurds veto power over a permanent constitution, scheduled to be created next year.
"If the leadership calls on us to withdraw from the government, we will do so," Kurdish Public Works Minister Nasreen Berwari told Reuters.
Between 60 and 65 percent of Iraq's 25 million people are Shiites, while Kurds number around 15 percent.
Kurds have been running their own autonomous region in northern Iraq since 1991, and many Kurds would prefer to have an independent country.
"Until now, we have not called for a separate Kurdistan, but if the Kurds' rights are not recognized, then we will take political measures that serve the interests of the Kurdish people," said Mulaha Bekhtiyar of the Patriotic Union of Kurdistan, one of two major Kurdish political parties. "For the time being, we will commit to a united Iraq."
Bekhtiyar also told the Associated Press that the Kurds would not agree to the Shiites having the "lion's share" of any government.
At the United Nations, Secretary-General Kofi Annan tried to reassure the Kurds, saying that while the resolution doesn't refer to the constitution, it "does have language that refers to a united federal democratic Iraq."
Meanwhile, clashes persisted Wednesday around Fallujah, a Sunni Muslim city west of Baghdad.
Rebels fired mortars at Iraqi forces that had taken over security in Fallujah at the behest of U.S. troops after a bloody counterinsurgency campaign there.
Iraqi officers told Reuters 12 of their men had been killed and 10 wounded in the attack on a camp housing the forces.
It was believed to be the first assault on the Fallujah Brigade since the unit took charge there last month.
In another attack, saboteurs Wednesday blew up an oil pipeline that disrupted supplies of crude from Kirkuk's oil fields to Iraq's biggest refinery at Beiji.
The blast cut supplies to the Beiji electric power station, forcing a 10 percent cut in electricity output.
It occurred at about 9:30 a.m. near Beiji, 155 miles north of Baghdad, said Col. Sarhat Qadir of the Kirkuk police. Huge fireballs rose into the air, witnesses told the AP.
Power cuts in Iraq are making it difficult to cope with soaring temperatures, which have already reached more than 100 degrees.
The U.S. government expects attacks on Iraq's infrastructure to continue.
"As we have been saying for some time, international terrorists and Saddam loyalists continue to try to derail the emergence of a modern democratic Iraq," Dallas Lawrence, a spokesman for the Coalition Provisional Authority, said in a statement quoted in The New York Times. "These terrorists hope that by damaging Iraq's infrastructure, by depriving Iraqis of basic services, they will be able to impoverish the Iraqi people and capitalize on a sense of frustration."
"They will not succeed," he added.