Afghan presidential election candidate Abdullah Abdullah on Wednesday demanded a halt to vote-counting over fraud allegations, raising the prospect of a political crisis during the country's first democratic transition of power.
Abdullah ramped up his complaints over alleged fraud in Saturday's run-off election by accusing his opponent Ashraf Ghani, outgoing President Hamid Karzai and the election authority of all being involved.
A smooth election was seen as a key test of the 13-year international military and aid effort to develop Afghanistan since the fall of the austere Taliban regime in 2001.
But Abdullah's statement on Wednesday fuelled a growing dispute that could trigger instability as the bulk of US-led troops withdraw from Afghanistan by the end of the year.
"We suspend engagement with the (election) commission and we have asked our monitors to leave their offices," Abdullah said.
"We are asking for the counting process to be stopped immediately."
He added that "everybody knows that unfortunately the president of Afghanistan was not impartial" and that some ballot boxes were stuffed with votes the day before the second-round election.
The dispute erupted despite pleas from the United Nations and the United States for Abdullah and Ghani to give officials time to conduct the count and adjudicate on fraud complaints.
Abdullah believes fraud denied him victory in the 2009 presidential race, and has often said that only widespread ballot-rigging could stop him from winning this time.
Counting the votes will take weeks. The preliminary result is due on July 2, before the official complaints period begins, and the final result is scheduled for July 22.
The two candidates went through to the run-off after coming top in the eight-man election on April 5, when Abdullah secured 45 percent and Ghani scored 31.6 percent.
Saturday's run-off was hailed a success by Afghan officials and international donor nations, despite more than 50 people killed in separate Taliban strikes on polling day.
The White House praised voters' courage and called the elections "a significant step forward on Afghanistan's democratic path".
Eleven voters in the western province of Herat had their fingers -- which were dipped in ink to register their ballot -- cut off by insurgents.
All NATO combat forces are due to withdraw from the country by December, though 10,000 US troops will remain into next year.
Karzai, who has ruled since the fall of Taliban in 2001, was constitutionally barred from standing for a third term.