KABUL (Reuters) - Almost as many donkeys as trucks will be used to take ballot papers to remote areas of Afghanistan for next months presidential election, which the UN chief envoy said on Tuesday was the most complicated hed ever seen. UN Special Representative Kai Eide visited a massive warehouse in Kabul where Afghanistans Independent Election Commission (IEC) is making final preparations for the huge logistical task presented by the Aug. 20 presidential poll. Afghanistans 17 million-odd eligible voters will cast their ballots in some 7,000 voting centres or 28,500 smaller voting stations across Afghanistans 34 provinces and 356 districts. Many will be set up on mountainsides or by rivers in remote areas where the only access is on the backs of donkeys. I emphasise that these are the most complicated elections I have seen, Eide told reporters. I mentioned to you how inaccessible the country is, how challenging the whole logistical operation is, and also the fact that the country is a country in conflict, he said. The election is being staged against the backdrop of increased violence across the country after thousands of US Marines and British troops launched major operations in southern Helmand province this month. The Helmand operations are the first under US President Barack Obamas new regional strategy to defeat the Taliban and stabilise Afghanistan. Washington is pouring in thousands more troops this year, in part to provide security for the election. Security is the foremost concern, with attempts made on the lives of two candidates, including President Hamid Karzais senior vice-presidential running mate, in the past week. Voter registration was conducted across Afghanistan late last year and early in 2009 except for five districts in Helmand, where poor security meant registration only began last week. Eide said security was an issue of concern and that the IEC and security forces were in the final phases of planning. The aim is to make as much of the country as possible secure for elections to take place, Eide said. Logistics in a country of vast deserts, and high, craggy mountains and valleys were almost as much of a challenge as running an election at the same time as a growing insurgency. A fleet of 3,500 trucks will carry voting materials to the polling stations, as well as 3,000 donkeys to get people to the most remote areas, Eide said. Local and international observers have warned that poor security and rampant corruption mean widespread voter fraud in either registration or the casting of ballots could be possible, but Eide said everything possible was being done to avoid that. Voters will have their fingers inked before casting ballots. There were complaints in the last election in 2004 that the ink could be rubbed off easily but Eide said that had been addressed. I challenge you to try and find a material that will take the ink away without taking my finger away, Eide said. President Hamid Karzai, seeking re-election after winning Afghanistans first direct elections in 2004, is a clear front-runner in a field of 38 challengers. He was widely criticised for pulling out of the first televised debate of the campaign last week against his two main rivals, former foreign minister Abdullah Abdullah and former finance minister Ashraf Ghani. It has not been perfect but it has been a good and informative campaign so far ... and I hope that that will encourage the Afghan people to come out and vote, Eide said. I think its been a quite vibrant debate where the candidates have, as we urged them to, behaved with dignity.