John Kerry has met rival Afghan presidential candidates for a second day in an effort resolve a disputed election that threatens to stir ethnic tensions and undermine a peaceful political transition.
The US secretary of state's talks on Saturday with Ashraf Ghani and Abdullah Abdullah were held after discussions on Friday proved inconclusive.
Kerry is pushing for a plan acceptable to both parties, which would allow the UN to audit fraud allegations in last month's vote.
Afghanistan's election commission declared Ghani the winner of the second round of voting on June 14, with 56.44 percent of the vote, according to preliminary results.
The tally might change when the final official numbers are released on July 22.
Abdullah, who won the election's first round, rejected the second round results as a "coup" against the Afghan people, saying the result was invalid because it did not throw out all the fraudulent votes.
Abdullah is a former anti-Taliban fighter, and of Pashtun and Tajik heritage. Ghani has strong support from Pashtun tribes in the south and east.
|Presidential candidates Ashraf Ghani (left) and Abdullah Abdullah (right)
Kerry has said that any effort to resolve the dispute through violence or any "extra-constitutional means," will cause the US to withdraw assistance to Afghanistan.
The US diplomat said that Washington was not taking sides with his hastily arranged meetings on Friday. Instead, it was focused on creating a process that ensures Afghanistan's next leader is viewed as legitimate, he said.
Kerry also met the incumbent president, Hamid Karzai, who is due to hand over power when an agreement is reached.
Violence continues to ravage the nation. On Saturday, at least 10 people were killed in separate roadside bombings in Kandahar province in the south and Nangarhar province in the east.
No group claimed responsibility for the attacks, but they come as the Taliban launched its spring offensive.