The United Nations special envoy to Afghanistan has described the upcoming presidential elections there as "the most complicated" he has ever seen.

Kai Eide on Tuesday praised the work of election officials, who face the difficult task of organizing the August 20 poll in a country where many regions are inaccessible to trucks and even helicopters.

Some 17 million Afghans are eligible to cast their ballots in about 7,000 voting centers.  A fleet of trucks will deliver voting materials to the polling stations, while more than 3,000 donkeys will ferry ballots to the most remote areas.

The election - the second in Afghanistan's short history as a democracy - is being held amid escalating violence.

On Tuesday, gunmen ambushed a convoy carrying a campaign manager for Afghan presidential candidate and former foreign minister, Abdullah Abdullah, killing a driver and wounding the campaign manager.    

Earlier this week, one of President Hamid Karzai's vice presidential running mates, Mohammad Qasim Fahim, escaped unharmed after Taliban insurgents opened fire on his convoy in northern Afghanistan.

In other violence Tuesday, a roadside bomb in southern Helmand province killed eight security guards and wounded four others.

In a nearby Zabul province, the NATO-led force said an Afghan civilian was killed and five others wounded after its troops clashed with insurgents.  A NATO statement said the wounded were treated at a NATO base, but one succumbed to injuries.

Thousands of U.S., British and Afghan forces are focused on bringing security to the volatile south ahead of the presidential election. 


Some information for this report was provided by AP and Reuters.