Security forces said they thwarted four massive rebel bombings, including a plan to blow up a large dam, underscoring fears for Sunday's vote that many hope will marginalize insurgents and bolster a fragile democracy.
U.S.-led coalition and Afghan troops caught 20 militants laying explosives along Kajaki Dam in southern Helmand province, Defense Ministry spokesman Gen. Mohammed Saher Azimi said. Thousands of people who live near the dam could have been killed if it burst.
Top U.N. envoy Jean Arnault said extremists had failed to disrupt preparations for the polls, despite fighting that has killed more than 1,200 people in the past six months, including seven candidates and four election workers.
"We are very confident that those extremists will also fail to disrupt and derail voting day," Arnault told a news conference.
Chief election organizer Bismillah Bismil appealed for voters to cast their ballots and not be "intimidated or frightened" by the threats of more bloodshed.
U.S. military spokesman Col. James Yonts predicted "a massive number" would turn out to vote.
"This election will send a powerful message to the Taliban that their influence is waning and that the overarching grip they've had on this country for several years is no longer there," he told The Associated Press.
Their comments came a day after the Taliban called for a boycott of the polls. They said they would not attack civilians going to vote, but would target areas where U.S.-led coalition forces were deployed, and advised people to avoid such places.
About 100,000 Afghan police and soldiers and 30,000 foreign troops are on alert across the country to safeguard the election. In Kabul, road checkpoints have sprung up, with police pulling over vehicles ranging from hay carts to ribbon-decked wedding cars.
In neighboring Pakistan, thousands of troops deployed near the Afghan border went on alert. Militants based in tribal areas on the Pakistani side of the mountainous frontier are believed to cross into Afghanistan to launch attacks.
In the southern city of Kandahar, all vehicles were banned from the roads after midday Saturday amid fears rebels were planning car bombings.
In an unusually brazen attack on the outskirts of the capital, militants ambushed a security patrol, killing a district police chief and two officers, said Interior Ministry spokesman Luftullah Mashal.
"This is the first attack so close to Kabul that we have seen in a long time," he said. "The Taliban and al Qaeda are trying their best to create problems."
Guerrillas also ambushed a police patrol on the main highway linking Kabul with the southern city of Kandahar, triggering a gunbattle that left seven militants dead, said Gulam Rasool, a government chief in Sharisafar district.
An insurgent rocket slammed into a police car, setting it afire, but all the officers inside escaped, he said.
Two Taliban rebels were also killed during fighting in Kandahar province Thursday, according to a Defense Ministry statement. Eight suspected rebels were arrested, it said.
Mashal said two of the thwarted attacks were planned car bombings in Ghazni and Paktika, two volatile provinces. The other was near the border with Pakistan, when two Pakistanis, suspected to be Taliban members, were found with explosives.
Election workers have been putting the final touches on poll preparations, using donkeys, dilapidated trucks and helicopters to haul millions of paper ballots to more than 6,000 polling centers.
Amid the killings, threats and concerns about pressure from powerful warlords, election organizer Bismil assured voters their ballots would be secret.
"Do not be intimidated or frightened by the empty threats of those who attempt to influence your vote," Bismil said.
The elections of a parliament and provincial legislatures are the last formal step toward democracy on a path set out after a U.S.-led force drove the hard-line Taliban from power in 2001.
"We are seeing today an unmistakable confirmation that there is in the country the emergence of a new political culture," Arnault said. "A sense that the legacy of the rule of the gun can be resisted is now taking root."
want these polls to bring peace and stability."