A bomb ripped through a bustling Kandahar bazaar Saturday, wounding 20 Afghans, in an attack the Taliban say targeted — but missed — U.S. soldiers.

The blast highlighted the new cycle of violence against soldiers and civilians that threatens plans for a national election supposed to cement Afghanistan's emergence from anarchy.

Taliban fighters claimed responsibility, saying the blast was aimed at American soldiers, but went off late.

The bomb, apparently attached to a parked motorcycle or bicycle, exploded in front of a hotel at about 12:30 p.m. in the city's main commercial district.

Six shops were leveled. Broken glass from the shattered hotel front littered the ground, stained by the victims' blood. The wounded included three children, Afghan state TV reported.

Qasim Khan, a Kandahar hospital doctor, said three of the 20 injured were seriously hurt and taken to the coalition military base at the city's airport for treatment.

The attack in Kandahar (search), once a Taliban stronghold in the south, was the latest by militants loyal to the former regime.

They often target civilians and appear determined to derail the first election in war-torn Afghanistan in many years. The vote is scheduled in June as part of U.S.-led efforts to democratize it and extend the government's power from Kabul (search), the capital, to rural areas where Taliban sympathizers and warlords are strong.

The coalition also is concerned that the Taliban could target a loya jirga (search), or grand council, in Kabul next week that is designed to debate and ratify a new Afghan constitution.

Speaking with the AP in Kandahar by satellite telephone, Taliban spokesman Mullah Abdul Hakim Latifi said the bomb was meant for U.S. soldiers shopping at the bazaar, but went off later than planned.

But an Afghan commander accused Taliban militants of deliberately hitting civilians.

"There was no American patrol at that time, and there is no government office there," the commander, Khan Mohammad, told The Associated Press. "It's just a market."

Latifi claimed that Taliban also were behind an attack Wednesday in Kandahar, that wounded two U.S. soldiers, one of them seriously.

President Hamid Karzai (searchand U.S. Secretary of Defense Donald Rumsfeld, who made a one-day visit to Afghanistan this week, insisted the presidential vote planned for June will go ahead.

Yet Afghan ministers and the United Nations say security must improve — with the aid of more foreign troops — to keep the vote fair and include all the country's bitterly divided ethnic groups, including the provincial warlords.

"The government is determined to hold to the timetable," Karzai's interior minister, Ali Ahmad Jalali, told reporters. "But if something happens we will have to make a decision on whether to wait."

U.N. officials say the violence will prevent them from sending workers to register voters in remote villages, a mammoth task that began in major towns only this month — two months late.

At least 11 aid workers have been killed in Afghanistan since March.

An explosion near the U.S. Embassy in Kabul on Thursday evening, about two hours after Rumsfeld left the country, underlined that the capital also remains unsafe.

Also Thursday, suspected Taliban militants opened fire on vehicles carrying Afghans working on a U.N.-sponsored census, killing one and injuring 11 in southern Helmand province.

Coalition forces also found hundreds of rockets, mortars and mines neatly stacked in Kandahar prison, from where 41 Taliban prisoners mounted a spectacular escape in October.