Baghdad, Iraq ? Final results from Iraq’s landmark referendum on a new constitution will likely not be announced until Friday at the earliest because of delays getting counts to the capital and a wide-ranging audit of an unexpectedly high number of “yes” votes, election officials said.

The returns have raised questions over the possibility of irregularities in the balloting. With the delays, the outcome of the crucial referendum will remain up in the air possibly into next week.

Meanwhile, insurgent attacks began to heat up again after being nearly silent on referendum day Saturday, when polling stations were heavily protected across the country.

A U.S. soldier was shot and killed in Mosul, 225 miles northwest of Baghdad, early Tuesday, the military said. In fighting in western Iraq, two U.S. Marines and four militants were killed Monday near the town of Rutba, not far from the Jordanian border, the military said. At least 1,980 members of the U.S. military have died since the beginning of the Iraq war in March 2003, according to an Associated Press count.

Gunmen killed the deputy governor of Anbar province, Talib Ibrahim, spraying his car with automatic weapons fire in Ramadi and wounding two of his bodyguards, police said. Anbar, the vast western Sunni region, is the main battleground between insurgents and U.S.-Iraqi forces.

Militants killed at least nine Iraqis elsewhere Tuesday in shootings and a mortar attack, including an adviser to the industry minister, one of the country’s top Sunni Arab officials, police said.

The handcuffed and mutilated bodies of six Shiites were pulled out of a pond where they were dumped north of Baghdad, and three other bodies were discovered elsewhere in the capital.

The election commission and United Nations officials supervising the counting have made no mention of fraud and have cautioned that the unexpected votes are not necessarily incorrect.

But Sunni Arab leaders who oppose the charter have claimed the vote was fixed in Ninevah and Diyala and elsewhere to swing them to a “yes” after initial results reported by provincial officials indicated the constitution had passed.

Both provinces are believed to have slight Sunni Arab majorities that likely voted “no” in large numbers, along with significant Shiite and Kurdish communities that largely cast “yes” ballots. But initial results from election officials in Ninevah and Diyala indicated about 70 percent of voters supported the charter and only 20 percent rejected.

Sunni opponents needed to win over either Diyala or Ninevah to veto the constitution. Sunnis had to get a two-thirds “no” vote in any three of Iraq’s 18 provinces to defeat the charter, and they appeared to have gotten it in Anbar and Salahuddin, both heavily Sunni.

After a sandstorm that had closed Baghdad’s airport cleared Tuesday, the first bags full of sheets of vote counts from Iraq’s provinces were flown into the capital for tabulation from Anbar, Karbala and Babil provinces. All of Baghdad’s vote counts have also reached the central counting center.

But the head of the Electoral Commission, Ezzeddin Mohammed, said material from 14 others were likely to be flown in today. The 250 workers at Baghdad’s central counting center will then take two days to go through them to produce a final count – meaning Friday.

The audit could further delay matters, Mohammed said. The electoral commission must send representatives along with U.N. officials to the concerned provinces to carry out the review.