KABUL - Four days after Afghanistan began a massive audit of millions of votes cast in the run-off presidential election, disagreements and a shortage of observers have slowed progress. The audit of all 8.1 million ballots cast in the June 14 run-off round was agreed by rival candidates Abdullah Abdullah and Ashraf Ghani, following a deal brokered by US Secretary of State John Kerry.The bitter impasse over the vote to succeed President Hamid Karzai, following Abdullah's claims of massive fraud, had plunged Afghanistan into crisis and raised fears of a return to the ethnic violence of the 1990s.The audit began last Thursday and the Independent Election Commission (IEC) said last week it was planned to take around three weeks, with teams working in two shifts auditing around 1,000 ballot boxes a day.But with only 435 ballot boxes checked since Thursday, the exercise is expected to take longer than planned."The process has been slower than expected. There are not enough international observers, the IEC was not ready for the process (when it was announced), it is a new experience for them," Fahim Naeemi, spokesman for a group called Free and Fair Election Forum of Afghanistan, told AFP."There are no criteria for the invalidation of unclean votes. They can audit, but they cannot invalidate votes yet." On Saturday the checking was briefly suspended by a dispute over a batch of potentially spoilt ballots.The contested ballot papers, whose number and origin were not specified, were deemed void by one candidate's team as they lacked a full name and signature, according to an IEC spokesman."The disagreement was on signatures on data forms, a candidate claimed they were not properly signed," spokesman Noor Mohammad Noor told reporters.As a result, the audit was suspended on Saturday evening until mid-afternoon on Sunday when agreement was reached, according to the IEC."In these kind of exercises, it isn't unexpected that there may be some teething problems," said spokesman Ari Gaitanis of the United Nations Assistance Mission in Afghanistan."The main thing is that the campaigns are still engaged and talking with each other on how to go forward." "The UN encourages both campaigns to maintain this spirit of cooperation," he added. The auditing at IEC headquarters is being watched by hundreds of national and international auditors including candidates' agents, local election monitors, UN and European Union observers."The European support for this audit in Afghanistan is unprecedented in the history of EU election observation missions around the world," Thijs Berman, chief of the European Union Assessment Team in Afghanistan, said in a statement."This audit is a necessary step. We have repeatedly called for it." Abdullah led Ghani after the first round of voting but preliminary results of the run-off, announced on July 7, showed Ghani ahead by over one million votes.Abdullah rejected the result, saying that most of his opponent's ballots were fraudulent.The audit is aimed at ending a political crisis that threatened to widen ethnic fissures as foreign troops prepare to withdraw by the end of the year.Abdullah draws his support from Tajiks and other northern Afghan groups, while Ghani is backed by Pashtun tribes of the south and east.There are around 23,000 ballot boxes that need to be audited. They are being transported by the Afghan army and NATO forces to the capital where they will be examined at 100 verification stations.