KABUL: Afghanistan's fraud-hit election teetered on the brink of collapse Wednesday as one of the two candidates boycotted the UN-supervised vote audit set up to end a prolonged dispute over the rightful winner.

Abdullah Abdullah, who claims that massive fraud was committed against him in the June 14 vote, pulled out of the audit after his senior campaign officials dismissed the process for invalidating fake votes as “a joke”.

The stand-off between Abdullah and his poll rival Ashraf Ghani has threatened to revive ethnic violence in Afghanistan as US-led Nato troops withdraw after 13-years of fighting the Taliban insurgents.

The audit of all eight million votes was halted on Wednesday morning when Abdullah's observers refused to participate — despite a US-brokered deal in which both sides vowed to support the recount and respect its outcome.

“We will not join the process today, and maybe we will not re-join the process at all,” Fazel Aqa Hussain Sancharaki, a spokesman for the Abdullah campaign, told AFP.

"Talks are ongoing with the UN. If that reaches an agreement, we will come back. If not, that is the end of it."

With both candidates claiming victory, outgoing President Hamid Karzai has upped the stakes by insisting that his successor is inaugurated next Tuesday.

The UN has voiced fears of a return to the ethnic divisions of the 1990s civil war if the election dispute sets off a spiral of instability.

Any backlash against the final result could split the country, since many of Ghani's supporters are Pashtuns in the south and east, while Abdullah's loyalists are Tajiks and other northern groups.