KABUL (AFP) - Five people were killed when an explosive device hit a vehicle being used by election staff in southeastern Afghanistan, a United Nations spokesman said.
"One electoral official and the driver and three other people who have yet to be identified were killed," said Manoel de Almeida e Silva.
He said the explosion occurred in Paktika province, which has many mines and other explosive devices.
The spokesman said the electoral commission, which organised the country's first presidential poll on October 9, was seeking further information on the incident to see if it was a deliberate attack.
The latest blast brings to at least 14 the number of electoral staff killed since registration began nationwide in May. More than 30 other electoral workers have been injured in attacks on vehicles and voter registration sites.
A wave of attacks expected from the country's former Taliban rulers on polling day failed to materialise and millions turned out to vote.
However, there has been a resurgence of violence since then with at least 20 people including two US soldiers killed -- mostly in the south and southeast where Taliban loyalists are waging a guerrilla campaign.
Afghan interim leader Hamid Karzai had a huge lead Monday with more than one million votes counted so far.