Attackers bombed a convoy carrying Afghan President Hamid Karzai's (search) running mate in northeastern Afghanistan (search) on Wednesday, killing one person and wounding five on the last day of campaigning before this weekend's landmark election.

The vice-presidential hopeful, Ahmed Zia Massood (search), escaped unharmed, said Khaleeq Ahmed, a spokesman at the presidential palace, but the former governor of Badakhshan, where the attack occurred, was among those injured.

Ahmed said the politician, Said Ikramuddin Masumi, would recover. Masumi was governor of Badakhsan until he stepped down recently to work on Karzai's campaign. He had not yet been replaced.

The convoy was apparently attacked by a roadside bomb or land mine set off by remote control as it passed along a road in Faizabad, the provincial capital, Ahmed said.

Mutaleb Beg, a local police official, said one person was killed and several others injured. Another official, Badakhshan criminal department chief Fazel Ahmad Nazari, put the number of injured at five. He said Massood was returning to Kabul by plane.

The attack came on the last day of campaigning for Saturday's landmark presidential elections, and as the United Nations declared the nation ready to hold the vote. Karzai addressed a throng of about 6,000 people at Kabul's sports stadium, telling the crowd that their vote would lay the "first bricks in a wall of democracy" in this war-shattered nation.

The U.S. Embassy, meanwhile, warned that the threat of attacks ahead of the election was high.

"In the run-up to the October 9 elections, potential continues to exist for demonstrations, riots, bombings, and other violent actions against U.S. citizens and interests in Kabul and the rest of the country," it said, urging extreme caution.

The area where Massood's convoy was attacked is not considered a haven for Taliban rebels and had been relatively peaceful in the past. It is, however, a center of Afghanistan's booming opium and heroin trade, with countless poppy fields dotting the landscape.

Ahmed, the palace spokesman, would not comment on who might be behind the attack, but he said whoever it is would not succeed in derailing Saturday's vote.

"The elections will continue 100 percent. We knew from day one that as we got closer to the elections, the enemies of Afghanistan would try to disrupt them, but they will not succeed, ever," he told The Associated Press.

Ahmed Zia Massood is the brother of slain northern alliance commander Ahmed Shah Massood. Karzai selected him as a running mate over current vice president and defense minister Mohammed Fahim, a Tajik faction leader.

In Kabul, the special representative for Afghanistan to U.N. Secretary-General Kofi Annan said that despite many problems, the elections will be fair enough to give Afghanistan's next ruler legitimacy.

"It is ... with full knowledge of the difficulties that surround this exercise that we deem the degree of freedom and fairness adequate to allow the will of the Afghan people as a whole to translate at the polls, and the next president of Afghanistan to claim to represent the nation," said Jean Arnault.

Speaking at Kabul's battle-scarred sports stadium, used as a public execution ground by the hardline Taliban regime until their ouster in 2001, Karzai urged the crowd to take part in the election.

"Your vote will elect a president for the next five years, but it will do much more than that as well," Karzai told the throngs. "By voting you are laying the first bricks in a wall of democracy that will last for decades and centuries in our country."

Some 6,000 people came out to hear Karzai speak, banging drums and shouting slogans like "Long Live Karzai!" and "Karzai is the future!"

Karzai is the overwhelming favorite to win Saturday's vote against 17 challengers, and he hopes the victory will add teeth to his often limited control of the vast, barren country.

During Taliban rule, the concrete sports stadium was the preferred execution ground for criminals and other outlaws. Its transformation into a place of democratic rallies is a dramatic example of how far the nation has come in the three years since a U.S.-led bombing campaign ousted the religious militia.

But the stadium is still pocked with thousands of bullet holes from a quarter-century of war, particularly the internecine feuds that leveled much of Kabul in 1992-1996, and stands as one of countless examples that the nation is still a shell of its former self.

Abdul Habib, a 60-year-old mechanic who was in the crowd, said he could remember the time when the same field was used for executions, carried out with a sword or a shot to the head. Criminals who were not killed often had their hands or feet cut off. Women were shot under their all-enveloping burqas, sometimes for no greater crimes than alleged adultery.

Karzai's rally was held before the attack on Massood, but even so it took place under extremely tight security.

It was at least the third attack on Karzai and his supporters since campaigning began on Sept. 7. Karzai survived a rocket attack on his helicopter on Sept. 16 as he was on his way to a campaign stop in the southeastern city of Gardez

Four days later, a roadside bomb in northern Afghanistan hit a convoy carrying Nayiamatullah Shahrani, one of four of Karzai's current vice presidents, injuring one of their bodyguards without harming the politicians, police said.