A top American official at the United Nations mission in Afghanistan has temporarily left the country following a disagreement with his boss over how to respond to the massive allegations of vote fraud in the Aug. 20 presidential election, officials said Tuesday.

The official, Peter Galbraith, a former U.S. ambassador to Croatia and currently the deputy special U.N. representative for Afghanistan, was in charge of political affairs. He left the country on Sunday.

The top U.N. official in Afghanistan, Kai Eide, said Galbraith himself suggested that he leave the country for a short time. Eide said he expects Galbraith to return.

"Primarily, we had a somewhat different approach to the election process," Eide told The Associated Press, explaining why Galbraith asked to leave.

Eide declined to say what the differences were that led to Galbraith's departure. He said there had been "no critical reaction" from the international community over Galbraith's leaving, including from the U.S. Embassy.

Galbraith and Eide will both be at the United Nations headquarters in New York at the end of the month for a quarterly Security Council update on Afghanistan, said U.N. spokesman Adrian Edwards.

The apparent disagreement between top U.N. officials exposes the tensions within Kabul's diplomatic community over how to respond to the election's messy aftermath. The U.N.-backed complaints commission announced Tuesday that ballots from about 10 percent of polling sites will have to be recounted because of possible fraud.

That increases the likelihood of a run-off between incumbent President Hamid Karzai and his top challenger Abdullah Abdullah who claims the election has been rigged in Karzai's favor. Resolving the election could take weeks and fears are growing of political unrest.

Eide said that he believes a second-round vote can be held before winter sets in if necessary.

Nearly complete preliminary results show Karzai with 54 percent and Abdullah with 28 percent, but Karzai is likely to lose thousands of votes after fraud allegations are examined, which could push him below the 50 percent threshold for outright victory.

Eide said that to delay any second round into next year would leave a dangerous political vacuum.

"To delay the process until summer next year, it would leave us without a legitimate government in a country that is in a serious armed conflict, and I think that's dangerous," he said.

But the departure of Galbraith raised questions about how much pressure the U.N. team here might be applying to election officials and whether the U.N. and U.S. see eye to eye on the counting process.

"Go to the U.S. Embassy and ask if they can put a razor blade between my position and their position. Our views are identical," Eide said. "It's tremendously important for me now not to be seen as doing anything else but slavishly follow the rules and laws that have been established. That to me is absolutely key. To be seen to deviate from that role in one way or another is dangerous."

A U.S. Embassy spokeswoman, Caitlin Hayden, said: "Our relationship with UNAMA is strong and stronger than it's ever been," referring to the U.N. Assistance Mission in Afghanistan.

Galbraith could not be reached for comment.

He arrived at his U.N. post in June. He worked for the U.N. in East Timor in 2000-2001 and as the U.S. ambassador to Croatia from 1993 to 1998.