KABUL — A proposal for the UN to mediate a crisis about allegations of election fraud gained momentum Friday as President Hamid Karzai backed the idea and the UN said it stood ready to help.
Abdullah Abdullah, who is running against Ashraf Ghani Ahmadzai for president, has accused electoral officials and others of trying to rig the June 14 vote against him. That has threatened what Western officials had hoped would be a peaceful transfer of authority, as Karzai is constitutionally barred from seeking a third term.
Underscoring the instability plaguing the country, a roadside bomb killed three American troops and a military dog Friday in southern Afghanistan, officials said.
Abdullah announced this week that he was severing ties with the Independent Election Commission and would refuse to recognize any results it releases. He also suggested that the UN step in. The IEC’s official timetable says initial results are due on July 2.
Karzai said he met with UN officials and spoke to Abdullah on the telephone about the issue. He also passed the message to Ahmadzai and said the candidates should choose between UN mediation or talks overseen by his two vice presidents.
‘‘I welcome any action to help end this political crisis,’’ he said during a meeting with senior Afghan clerics in Kabul.