US Secretary of State John Kerry has urged the 2 presidential contenders in Afghanistan to cooperate in the investigation into allegations of vote fraud.
Kerry arrived in the Afghan capital Kabul on Friday to meet separately with former finance minister Ashraf Ghani, and former foreign minister Abdullah Abdullah.
Preliminary results of the run-off presidential election held last month show Ghani leads Abdullah by more than 10 points. But Abdullah rejected the result and threatened to set up an alternative administration, saying there was massive fraud.
The UN is proposing an investigation of 3.5 million votes suspected of being fraudulent, which account for more than 40 percent of the total vote.
Kerry asked the two contenders to cooperate in the investigation.
While Ghani expressed support for the proposed investigation, Abdullah demanded the resignation of the head of the panel investigating the suspected fraud and called for a broader investigation.
It is unclear whether Abdullah's' demand will be accepted.
Kerry will stay in Kabul until Saturday to hold further talks.
Most of the US-led international forces are planning to withdraw from Afghanistan by the end of this year.
US officials are concerned the confrontation could raise ethnic tensions and affect their withdrawal plan.
Jul. 11, 2014 - Updated 16:28 UTC