BAGHDAD - Iraq's chief spokesman acknowledged differences with the United States over a proposed long-term security agreement and pledged yesterday that the government will protect Iraqi sovereignty in ongoing talks with the Americans.

Chief government spokesman Ali al-Dabbagh said that the Iraqi negotiators have a "vision and a draft that is different" from the Americans' but that the talks, which began in March, were still in an early stage.

"There is great emphasis by the Iraqi government on fully preserving the sovereignty of Iraq in its lands, skies, waters and its internal and external relations," Dabbagh said. "The Iraqi government will not accept any article that infringes on sovereignty and does not guarantee Iraqi interests."

Opposition has been growing in Iraq to the proposed security pact with the United States, which will replace the current U.N. mandate and could provide for a long-term American military role in this country.

Much of the opposition comes from anti-American Shiite cleric Muqtada al-Sadr, but statements critical of the deal have also been issued by mainstream Sunni and Shiite figures who fear it will undermine Iraqi sovereignty.

U.S. officials have refused to comment on the talks until they are complete but have insisted they are not seeking permanent bases. The agreement is to replace a U.N. mandate for U.S.-led forces that expires at the end of the year.

President Bush and Iraqi Prime Minister Nouri al-Maliki said they were hoping to finish the negotiations by July to allow time for the Iraqi parliament to sign off on the deal.

But Iraqi officials said last month that talks were unlikely to wrap up by July because of wide differences over several issues, including U.S. troops' immunity from prosecution in Iraqi courts and rules governing U.S. military operations.

Yesterday, Australia became the latest member of the U.S.-led coalition to pull combat soldiers from Iraq, fulfilling an election promise that helped sweep Prime Minister Kevin Rudd to power in November.

Australia, one of the first countries to commit troops to the Iraq war five years ago, ended its combat mission here and began sending its 550 combat troops home.

Rudd, the new prime minister, has said the Iraq mission had made Australia more of a target for terrorism and had promised to bring home his country's combat soldiers by the middle of this year.