KABUL, Afghanistan — The worst helicopter crash in four years killed nine people here, bringing NATO fatalities in Afghanistan in 2010 to 529 and making it the deadliest year since the war began in 2001.
The crash was in the Zabul province in southern Afghanistan early Tuesday. An explosion later brought the death total for the year to 530.
Pentagon officials said most of the dead were Americans.
Meanwhile, a report released on Tuesday on violence and voter fraud in the recent election could make it harder for the Obama administration and the international community to portray Afghanistan's second parliamentary election since 2001 as a step forward in consolidating the country's shaky democracy and containing the Taliban.
The helicopter crash was the deadliest for NATO forces in Afghanistan since one that killed 10 soldiers in Kunar province in May 2006.
The statistics on NATO deaths were compiled by icasualities.org, a website that tracks military casualties. The Associated Press had a different tally, reporting on Tuesday that at least 524 U.S. and NATO forces have been killed in Afghanistan so far this year.
There was no sign of enemy fire in the area, but the helicopter crash is under investigation.
The Taliban have long been entrenched in many areas of Zabul province, and a Taliban spokesman claimed responsibility for what they said had been an attack on the helicopter but offered no details. The Taliban often claim credit for attacks that kill NATO service members, even when mechanical failure is to blame.
Tuesday's crash occurred near the district center of Diachopan District, according to Muhammad Jan Rasoolyar, a spokesman for the provincial governor. Zabul, which lies just to the east of Kandahar province and borders Pakistan, is sparsely populated with large areas of desert, low mountains and small villages.
The crash also injured one NATO service member, an Afghan army soldier and a U.S. civilian.
Later, in another attack in southern Afghanistan, a NATO service member died when a roadside bomb exploded under his vehicle in southern Afghanistan.
Six Afghan security guards also died Tuesday when a roadside bomb exploded as they were driving in the Shinwari District of Parwan province, according to Gen. Basir Salangi, the provincial governor. The security guards, who worked for Haji Naveed Construction Co., were guarding workers who were paving a 45-mile stretch of road that connects Parwan with neighboring provinces.
The company's employees had received repeated threats by phone from the Taliban and demands for money, Salangi said.
Violence is 69 percent higher for the three months ending Sept. 14 than it was for the same period last year, according to the U.N. special representative's quarterly report to the Security Council, which was released Tuesday.
The deterioration of security was most evident in the increase in roadside bomb explosions, which rose 82 percent over the same period in 2009. One bomb was aimed at a U.N. convoy in Parwan province, killing three police escorts and a driver.
Suicide bomb attacks also doubled from the same period last year, and insurgents accelerated their assassination campaign. Twenty-one people were reported assassinated per week on average, compared with seven during the same period last year.
The worst recent attack on humanitarian workers occurred Aug. 6, the report said, when 10 members of an international medical mission were executed by Taliban fighters in Badakhshan province, where they had traveled to deliver free medical services including eye exams and prenatal care.
Meanwhile, internal reports from Afghanistan's Independent Election Commission on Tuesday provide new evidence of serious fraud in Afghanistan's parliamentary elections, including turnouts that exceeded 100 percent in many southeastern districts under the control of the Taliban or other militants.
One district in Paktika province recorded 626 percent voter turnout, according to reports obtained by McClatchy Newspapers.
The new indications of fraud appear to strengthen allegations of widespread intimidation, vote rigging and violence that independent Afghan monitors began making almost immediately after the polls closed on Saturday and cast new doubts on the commission's assertion that it knew of no instances in which commission staff members stuffed ballots.
An independent analysis, meanwhile, estimated that the number of violent incidents during Saturday's contests for Parliament's 249-seat lower house was higher than it was for last year's fraud-marred presidential election.
Indicum Consulting, a Kabul-based private security analysis firm, estimated that there were as many as 600 insurgent attacks on Saturday, compared to about 450 in the 2009 presidential contest.
"The amount of violence on polling day, especially early morning, was clearly higher this year than during the presidential election, and threats and attacks closed down a fairly huge amount of polling centers," said Sami Kovanen, Indicum's senior information analyst.
The commission polling reports document district-by-district breakdowns of voter turnouts in Paktika, Paktia, Zabul and Ghazni provinces in Saturday's contests for Parliament's lower house, the Wolesi Jirga.
The reports put 10 districts as reporting attendance that exceeded 100 percent and one reporting precisely 100 percent, a glaring indication of fraud.
Information from McClatchy Newspapers was used in this report.