KABUL - The United Nations is confident Afghanistan's election can be resolved before winter, with ballots already being printed to hold a second round if a fraud investigation makes that necessary, a spokesman said on Sunday.

Preliminary results show president Hamid Karzai with 54.6 percent of the vote -- enough to win the August 20 poll in a single round -- but a U.N.-backed watchdog has ordered a partial recount because of fraud.

If the recount eliminates enough of Karzai's votes so that he no longer scores more than 50 percent, a second round must be held against his main opponent, former foreign minister Abdullah Abdullah.

A senior Afghan election official said on Saturday that a second round, if necessary, would have to be held by the third week in October or be postponed until next year because of harsh weather that makes much of the country inaccessible.

That would give the fraud investigators just two weeks to complete their recount to allow two more weeks for campaigning.

U.N. spokesman Aleem Siddique said he was confident the recount could be completed fast enough to either crown Karzai the victor in the first round or hold the run-off this year.

As a precaution, officials have already ordered ballot papers printed up for the possible second round, he said.

We all recognize the difficulty in holding a second round as winter approaches, but all that does is increase our determination to put all our efforts into having a second round this year, if it's needed, Siddique said.

INVESTIGATING FRAUD

The U.N.-backed Electoral Complaints Commission has ordered a recount of about 10 percent of polling stations after finding clear and convincing evidence of fraud.

An EU observer mission describes as suspicious more than a quarter of votes, including more than a third of those cast for Karzai. The president acknowledges some fraud, but says its extent was exaggerated by the media and foreign observers.

Afghanistan's election commission has been discussing with the U.N.-backed ECC how to carry out the recount it ordered as quickly as possible to avoid postponment of a run-off.

Western diplomats say putting off a second round until next year could make Afghanistan more unstable.

Siddique said the fraud investigation could be speeded up by testing a sample of ballots from suspicious polling stations and using mathematical models to determine whether the fraud could have been extensive enough to overturn Karzai's victory.

This is a question of mathematics, he said. You just have to make sure that the sample size is large enough.

(Editing by Ron Popeski)

Afghanistan Winter