BAGHDAD, Iraq (AP) -- Iraq's interim president said Tuesday that tens of thousands of people were unable to vote in the country's historic weekend election because some polling places -- including those in Sunni Arab areas -- ran out of ballots.

As clerks pounded vote-count tallies into computers to compile final results, interim President Ghazi al-Yawer also said chaos and a power vacuum in Iraq meant that U.S. forces need to stay for now, even though a new government would be formed after the results are known.

He said foreign troops should leave altogether only after Iraq's security forces are built up, the country's security situation has improved and some pockets of terrorists are eliminated.

The allegation that many voters were turned away could further alienate minority Sunnis, who already are complaining they have been left out of the political process.

"Tens of thousands were unable to cast their votes because of the lack of ballots in Basra, Baghdad and Najaf," al-Yawer, himself a Sunni Arab, said at a news conference. Najaf is a mostly Shiite city, but Basra and Baghdad have substantial Sunni populations.

Elections officials admitted irregularities kept people away -- including in the volatile northern and heavily Sunni city of Mosul. Security worries in Sunni areas were partly to blame for the fact that some polls did not open and ballots were too few, they said.

"The elections took place under difficult conditions, and this undoubtedly deprived a number of citizens in a number of areas from voting," said Abdul-Hussein al-Hendawi, who heads the Iraqi electoral commission.

Sunday's election, which occurred without catastrophic rebel attacks, raised hopes that a new Iraqi government would be able to assume greater responsibility for security, hastening the day when the 170,000 U.S. and other foreign troops can go home.

The first visible reduction could come as soon as March, when thousands of U.S. troops whose tours were extended before the election are due to go home. If commanders allow the full rotation out and others are not brought in, it would shrink the overall force to 138,000.

But the timing of cutbacks beyond that is highly uncertain. U.S. administration officials are determined to avoid setting a specific timetable.

Meanwhile, January was the third month since the U.S. invasion of Iraq that U.S. troop deaths reached or exceeded 100. According to the Pentagon's latest count, at least 100 died in January, while an Associated Press tally put the figure at 102. The only months deadlier for U.S. troops were November, when 138 died, and April, with 135. More than 1,400 troops have died in Iraq since the war began in March 2003.

Scattered clashes were reported Tuesday in rebel areas across the country, but authorities still eased security restrictions by reopening borders and allowing commercial flights to take off from Baghdad Airport for the first time since the weekend's landmark election.

Violence included clashes in Mosul between insurgents and Iraqi National Guards, officials said. A person was killed and another injured. A roadside bomb also killed four guardsmen there.