BAGHDAD, Iraq — A week after the draft constitution was declared final, discreet talks were under way to refine language in a bid to win Sunni approval and ease fears of Iraq's Arab neighbors that the charter will loosen the country's ties to the Arab world, officials said yesterday.

Meanwhile, the U.S. military said two American soldiers were killed Thursday in Baghdad after their patrol was struck by a roadside bomb and a third was shot to death Wednesday in the central Iraqi city of Iskandariyah.

At least 1,886 members of the U.S. military have died since the Iraq war started in March 2003, according to an Associated Press count.

As negotiators discussed possible changes to the draft constitution, thousands of Shiite supporters and Sunni opponents of the document took to the streets yesterday to express their views ahead of the Oct. 15 referendum.

In continuing sectarian violence, unidentified gunmen opened fire on Sunni Muslim worshippers yesterday in two mosques south of Baghdad, killing two people and injuring four, police said.

Sunni Arabs rejected the charter that was approved Aug. 28 by the Shiites and Kurds, who dominate Parliament and government. The Sunnis cited a number of points, including federalism, references to Saddam Hussein's Sunni-dominated party and the description of Iraq as a Muslim — but not Arab — country.

Sunni opposition threatens a divisive political fight in the run-up to the referendum, sabotaging Washington, D.C.'s hopes that the constitution would serve to unite Iraq's population, lure the minority away from the insurgency and hasten the day U.S. and other foreign soldiers could go home.

Iraqi authorities also plan to delay the start of Saddam's first trial until four days after the referendum to avoid further polarization, a judicial official said on condition of anonymity because he's not authorized to talk to the press.

With the stakes so high, the United States has been pushing the factions to continue efforts to overcome differences, even though the law forbids further changes in the draft.

"Discussions are under way to make minor changes in the language to improve the text to satisfy some parties," Shiite negotiator Khalid al-Attiyah said.

Sunni Arab and Kurdish negotiators confirmed talks were continuing, but a Western diplomat cautioned against speculation of dramatic changes.

"We understand there is ongoing dialogue between Sunni negotiators and the Shiites and Kurds," said the diplomat, who declined to be identified because he was not authorized to comment on the process.

"We don't have the specifics of what is being negotiated, but we know they are discussing language changes and slight modifications that would bring the sides closer," the diplomat said.

In mostly Shiite Basra, Iraq's second-largest city, an estimated 5,000 people marched in support of the constitution, carrying banners saying it would bring "freedom and justice."

But about 2,000 mostly Sunnis staged an anti-constitution rally in Tikrit, Saddam's hometown. A smaller anti-constitution rally was held outside a Sunni mosque in Ramadi.

The goal of the ongoing talks is to produce a document that may not win public approval by Sunni negotiators but could appeal to enough moderate Sunnis that the charter would win the October referendum.

If two-thirds of the voters in any three of the 18 provinces reject the charter, it would be defeated. Sunnis form the majority in four provinces, although they make up only 20 percent of Iraq's population of 27 million and their margin in two of those provinces is not overwhelming.

In the mosque violence, a gunman opened fire inside the Mizael Basha mosque near Basra, killing one and injuring four, police said. A guard was killed when a group of gunmen attacked another mosque.