KABUL, Afghanistan - Afghanistan has thrown out nearly a quarter of ballots cast in last month's parliamentary elections because of fraud, according to full preliminary results released Wednesday.

The findings, which confirmed earlier reports, indicated that cheating was pervasive in the Sept. 18 vote that many hoped would show the Afghan government's commitment to reforming its corrupt bureaucracy.

But observers also praised the voided ballots as an achievement because it meant that the election officials had kept fraudulent ballots out of the totals.

That's a major change from last year's disastrous presidential election, when election commissioners dumped obviously fraudulent ballots into the tally to help President Hamid Karzai avoid a runoff with his top challenger. It was only after drawn-out investigations that about a million ballots were thrown out -- the majority of them for Karzai.

The 2009 presidential election nearly derailed international support for Karzai, turning this year's poll into a test of whether the government is committed to reforms seen as key for justifying NATO funding and troops.

Election commission chairman Fazel Ahmad Manawi said about 1.3 million votes were disqualified out of 5.6 million -- meaning about 23 percent of ballots -- because of ballot-box stuffing or manipulated totals.

It was not immediately clear what the results released Wednesday would mean for the makeup of the 249-member parliament.

Manawi said he did not have figures on how many of the winners were incumbents, though he said he believed it was about a 50-50 split between those who were returning and new representatives.

Though Karzai has repeatedly bypassed the parliament by issuing laws by decree, the legislative body also is one of the few checks on Karzai's power. A legislature loaded with Karzai allies could make it easier for the president to avoid opposition.

Election officials called the vote a success because they were able to catch the fraud, but the large number of disqualified ballots may tarnish the outcome.

It's possible that those living in provinces with a large number of disqualified ballots could claim that their legitimate ballots weren't counted. And in ethnically mixed provinces, there's a chance that the invalidations may favor one ethnic group over another.

A five-member fraud investigation panel also still needs to rule on more than 2,000 complaints deemed serious enough to affect results before they can be finalized. It was unclear when that would happen.

The election commission previously indicated it would take about three weeks after the preliminary tally was released, but officials would only say Wednesday that final results would be released as soon as possible.

Some candidates may also be disqualified outright if the anti-fraud panel finds that they were behind attempts to manipulate results. The election commission has referred 224 candidates to the panel for investigation because they appeared to be involved in cheating, Manawi said. About 2,500 candidates ran across 34 provinces.

The commission had originally reported a lower turnout figure of about 4.3 million. That earlier figure was based on election day estimates and revised up when the actual tallies came in, said Abdul Ahmadzai, the commission's chief electoral officer.

Asked why the number of disqualified votes matched so neatly with the revised turnout figure, Ahmadzai said it showed that the 4.3 million figure was probably more accurate and that the tallies were later inflated.

In another development, Karzai rejected pleas from the international community to reverse his order to disband all private security companies, saying money spent on those firms should be invested in the national police force instead.

The president has ordered Afghan and international security companies -- which protect everything from development projects and NATO supply convoys to private houses -- to disband by the end of the year. The decision has drawn criticism from the U.S. and others who worry the Afghan security forces are not ready to assume the burden.

But Karzai told reporters Wednesday he was tired of hearing complaints from embassies about the order, and said his decision to shut them down was final.

"We hope that our international friends will not get back to us or try to put pressure on us or talk about it in the media because none of these are going to work," he said. "These companies are closed -- that is it."

Also Wednesday, a NATO soldier was killed in a bomb attack in southern Afghanistan, the coalition said in a statement. No further details were provided.

Afghan and NATO soldiers also killed more than 10 armed insurgents during an overnight raid in Ziruk district of eastern Paktika province, NATO said Wednesday.

And in southern Nimroz province, eight children and one adult were killed and 10 were wounded when a girls' school bus hit a land mine, NATO said in a statement. The road is often used by NATO or Afghan troops.