KABUL - Afghanistan's U.N.-backed election watchdog will treat presidential candidates as equally likely to be guilty of vote fraud in suspicious cases, new rules issued on Monday show, a move that may ensure a win for Hamid Karzai.

Preliminary results showed the incumbent Karzai with 54.6 percent of the vote in Aug 20 vote, but the Electoral Complaints Commission has ordered a recount of 12 percent of ballot boxes after finding clear and convincing evidence of fraud.

Karzai would have to face his main rival, former foreign minister Abdullah Abdullah, in a second round if a fraud investigation lowers his share of the vote below 50 percent.

For that to happen, however, the complaints commission would have had to have found that a much larger share of Karzai's votes was fraudulent than that of his rivals.

The ECC published its recount rules on Monday, saying candidates would have ballots nullified in proportion to the total number of ballots they have in boxes considered suspicious, regardless of which candidate perpetrated the fraud.

The arithmetic appears to favor Karzai.

Under the recount rules, ballot boxes considered suspicious are grouped into six categories according to the grounds for the suspicion, but are not separated according to which candidate benefitted from the suspected fraud.

The complaints watchdog will look at 10 percent of the suspicious ballot boxes in each category, determine what share of the boxes were fake, and then reduce each candidate's tally of votes in that category by the same percentage, it said.

The ECC will determine the extent to which its findings about the samples affect the overall results of the presidential election, the body in a statement.

It will do so by determining what percentage of valid votes in the sample are fraudulent and then multiplying this percentage by the total vote for each candidate in the corresponding category, not counting those votes already in the sample.

The head of the Election Complaints Commission was appointed by the United Nations envoy in Afghanistan, Kai Eide.

Eide has been accused by his former deputy, U.S. diplomat Peter Galbraith, of turning a blind eye toward fraud, which Galbraith says was carried out overwhelmingly on behalf of Karzai and was big enough to prevent a second round.

Karzai has acknowledged that some fraud took place, but says the extent of it was exaggerated by Western officials and media.

Abdullah told Reuters he was looking into the recount rules to see whether they were fair. Karzai campaign official Arsala Jamal said he was also looking into the matter and had no immediate comment.

Afghanistan