By Hamid Shalizi and Tim Gaynor
KABUL (Reuters) - At least one person was killed when police fired into the air to disperse angry anti-U.S. protesters in the Afghan capital on Wednesday, highlighting security concerns three days before a parliamentary election.
The Taliban have threatened to disrupt the poll and Western observers also fear fraud will tarnish the vote. Afghanistan's own election watchdog warned of a "disputatious" process.
The election for 249 seats in the wolesi jirga, or lower house, is a test of stability in Afghanistan ahead of President Barack Obama's strategy review in December, a review that will likely examine the pace and scale of U.S. troop withdrawals.
It will also be a test of credibility for President Hamid Karzai after a fraud-marred presidential vote last year, with Western observers warning that a repeat of that drawn-out and flawed poll would weigh heavily on Karzai's allies.
Thousands of protesters chanting "Death to America," "Death to Christians," and "Death to Karzai" gathered in Kabul's west on Wednesday, the biggest protest since unrest erupted last week over plans by a U.S. pastor to burn copies of the Koran.
It followed three days of protests at the weekend staged even though the pastor abandoned his plan to burn copies of Islam's holy book to mark the ninth anniversary of the September 11 attacks.
The protesters burned tyres and blocked a main highway link to the south, with thick black smoke rising above the area as police moved in.
Police were ordered to advance toward one group of hundreds of protesters who were throwing stones and shouting "Death to American slaves." Police were then seen firing into the air and dragging some of the protesters away.
A police source later said one person had been killed and five wounded. Three people were killed in earlier protests, which the top U.N. diplomat in Afghanistan has warned could force the election to be delayed.
Reuters television pictures showed protesters waving large white flags, the symbol used by Taliban supporters.
Afghanistan's leaders have said their police and soldiers are ready to secure the election, with the almost 150,000 foreign troops acting in a backup role to be called on if needed.
On Wednesday, the NATO-led coalition said an air strike had killed a Taliban commander on Tuesday in a province west of Kabul who was planning to disrupt the vote.
The coalition also said three insurgents had been arrested in the capital for planning a rocket-propelled grenade attack on a military training center during the poll.
Authorities have also said they are guarding against fraud and were not concerned by the discovery of thousands of fake voter registration cards across the country. They said steps had been taken to ensure the cards could not be used.
Complaints by disgruntled candidates however threaten to drag the process out. There are almost 2,500 candidates and 1,089 complaints have already been received by the U.N.-backed Electoral Complaints Commission (ECC), said South African Johann Kriegler, one of two foreign ECC commissioners.
"It's going to be a disputatious election because you have a large number of candidates competing for a small number of seats," Kriegler told a news conference in Kabul.
He said the eventual number of complaints lodged over the election period could be "twice as many, three times as many." Of those received so far, 588 complaints have been settled.
Adjudicating on potentially thousands of complaints could delay the results of the ballot, with preliminary results not expected before October 8. A final result will not be released before October 30, but those dates could be pushed back further if a large number of complaints are lodged with the ECC.
Complaints received so far range from intimidation of candidates and voters to improper use of government services in support of particular candidates and unfair campaigning.
The ECC threw out a third of votes cast for Karzai last year as fake. Karzai drew international criticism after the vote when he ruled that the number of foreign ECC commissioners would be cut from three out of five to two.
The United Nations, however, has insisted this year that no ECC decision will be ratified unless at least one of the foreign commissioners agrees. (Additional reporting by Sayed Salahuddin and Jonathon Burch; Writing by Paul Tait; Editing by Sugita Katyal)