A U.N. helicopter sent to retrieve ballots crash-landed Tuesday in the snowy mountains of northeastern Afghanistan, electoral officials said.

Nobody was injured and no ballot boxes were on board, but the accident was the latest snag holding up the massive task of recovering votes in the country's first presidential election.

The helicopter went down at high altitude in an area of rugged Badakhshan province (search) known as the Wakhan corridor (search), which borders China, Tajikistan and Pakistan, said David Avery, chief of operations for the Joint Electoral Management Body.

The plane had yet to pick up any ballot boxes, but its loss will slow the recovery of ballots in the landmark presidential vote that took place Saturday, Avery said. The province has about 360,000 registered voters.

"We don't think we'll be able to recover the helicopter," Avery said.

The U.S. military was air-dropping warm clothes and food to help eight survivors from the crash survive the freezing night before a planned rescue operation on Wednesday, U.N. spokesman Manoel de Almeida e Silva said. He said the helicopters suffered an engine failure.

The tally of votes from Saturday's election was to begin Wednesday at the earliest, and final results were not expected until late October.

Chances for a conclusive result improved Monday after interim President Hamid Karzai's (search) main challenger, ethnic Tajik candidate Yunus Qanooni (search), backed away from a boycott of the vote, indicating he'd accept an independent commission to investigate vote-fraud allegations.

Karzai is the clear favorite to win, but his ability to consolidate his rule would be undermined if the opposition refuses to acknowledge the vote results.

German Chancellor Gerhard Schroeder (search), the first foreign leader to visit since the election, all but declared Karzai the winner on Monday.

In addition, an exit poll conducted by an American group closely tied to the Republican Party projected Karzai would win with the outright majority needed to avoid a second round.

The survey by the International Republican Institute (search) said Karzai would finish ahead of Qanooni by an overwhelming 43 percentage points. The group did not release a full breakdown of its data.

Qanooni said he would accept an investigation by an independent panel of election experts into opposition complaints that the supposedly indelible ink used to mark voters' thumbs in some polling stations could be rubbed off, allowing some to vote more than once.

"I don't want to be against the election and I appreciate the good will of the people of Afghanistan," Qanooni said. "I want to prove to the people of Afghanistan that the national interest is my highest interest."

He said he made his decision after a meeting with U.N. representative Jean Arnault (search) and U.S. Ambassador Zalmay Khalilzad (search).

The announcement followed similar statements Sunday by Massooda Jalal (search), the only female presidential hopeful and ethnic Hazara candidate Mohammed Mohaqeq (search).

There were indications another rival, ethnic Uzbek warlord Abdul Rashid Dostum (search), might be considering backing down as well. Dostum traveled to Kabul Tuesday from his home in the north, and his spokesman said he was considering accepting a compromise.

Electoral officials say the candidates have until Tuesday afternoon to submit formal protests, and the officials were waiting to receive them before they began the count.

Election organizers agreed to set up the panel Sunday in hopes it would end the crisis that emerged when all 15 opposition candidates declared the boycott while voting was under way Saturday.

The election has been hailed as a success by U.N. officials, Bush and other world leaders. International electoral observers have said the attempt to nullify the vote was unjustified.

Schroeder said the poll "was a great step toward democracy and stability" and predicted a Karzai win. "It is my opinion that he will do it, and in the first round," he said.

A high voter turnout in Afghanistan, which never before has tasted democracy, and a failure of Taliban rebels to launch a massive attack have also been held up as proof of success.

In the latest in a series of minor attacks, five rockets slammed into Kabul not far from the U.S. Embassy on Monday, killing a 16-year-old Afghan and damaging a house, officials and witnesses said.