A suicide bomber riding a motorcycle packed with explosives rammed into a car carrying the deputy governor of Afghanistan's southern Kandahar province on Saturday, killing him and wounding three of his bodyguards, the Interior Ministry said.

The attacker struck as the official, Abdul Latif Ashna, was being driven to work in the provincial capital, said a ministry spokesman, Zemeri Bashary.

The Taliban claimed responsibility for the attack. In a text message to reporters, Taliban spokesman Qari Yousef said the suicide bomber killed the deputy governor as well as three of his body guards and his driver.

U.S. ambassador to Afghanistan, Karl Eikenberry, who was traveling in Kandahar, and Afghan President Hamid Karzai condemned the assassination.

Kandahar, located in the Taliban's traditional southern stronghold, has been the scene of several attacks recently. Two weeks ago a bicycle bomb targeting police vehicles near the city center wounded at least 10 people _ six civilians and four police. Last month, a suicide car bombing in the city center killed three people and wounded 26 others, most of them police.

"The enemies of Afghanistan cannot stop the Afghan people from development and progress by killing such personalities," Karzai said in a statement. "There are thousands of other brave Afghans who will stand against the enemy and serve the people."

Also on Saturday, Karzai expressed his sadness over the deaths of six members of a prominent Afghan family who were killed when a Taliban suicide bomber blew himself up Friday at Kabul supermarket frequented by affluent Afghans and foreigners.

In a statement, Karzai said Dr. Massoud Yama, a young doctor at a military hospital, his wife, Hamida Barmaki, a political science professor at Kabul University, and their four children died in the attack. She was an activist and served on the Afghan Independent Human Rights Commission.

Yama's mother and Barmaki's mother-in-law is former Afghan senator Maboba Hoqiqmal, who currently is Karzai's legal affairs adviser.

Afghan police officials said initially that two or three foreigners were among eight people killed in the bombing. However, the Kabul Police Department released a statement Saturday evening saying that no foreigners died in the incident. So far, no foreign embassy has confirmed the death of any foreign victims.

Mohammad Zahir, the chief of criminal investigation for the Kabul police, said one man, one boy and six females _ all Afghan _ died in the blast. Fifteen other people were injured in the explosion _ 10 Afghans and five foreigners, he said.

The Taliban said their target was an official with the U.S.-based Xe security contractor, formerly known as Blackwater. A representative for USTC Holdings, which recently bought the North Carolina-based Xe, said no one associated with the company was killed or wounded in the bombing.

A senior international intelligence official in Kabul said Saturday that the Taliban's Haqqani network, which has ties to al-Qaida, carried out the attack, but that there was no intelligence to suggest that the security contractor was being targeted. The official spoke on condition of anonymity to disclose the information.

Elsewhere in the capital, more than 200 demonstrators rallied at the Iranian Embassy to protest the execution of Afghans in Iran and call on Tehran to release Afghan political prisoners. Similar protests, all organized by the National Solidarity Party, attracted hundreds of other demonstrators in Mazar-i-Sharif in northern Afghanistan and Herat in the west.

Protesters in Kabul carried signs that said "Death to Iranian President Mahmoud Ahmadinejad," showed photographs of Afghans held in Iran and depicted blood dripping from the red stripe of the Iranian flag.

Afghan lawmakers have claimed that as many as 45 Afghans had been executed in Iran, but the Afghan Ministry of Foreign Affairs has said that number is exaggerated. The ministry, which has raised the issue with Iranian officials in Tehran, has confirmed the execution of six Afghans in Iran but has not provided details about why they were killed.

"The ones fighting for freedom have been jailed in Iran," said Mohammad Yama, who helped organize the protest in Kabul. "We are here to show our unity. We wanted to burn down our effigy of Ahmadinejad, but the Afghan police took it away."

In a ceremony at the Afghan Ministry of Defense, the deputy chief of staff for operations of the U.S.-led coalition, John W. Nicholson, was promoted to the rank of major general and will now be the force's point man for transferring the responsibility for security from international forces to Afghan ones by the end of 2014.

The Afghan Army's Chief of Operations, Lt. Gen. Sher Mohammad Karimi, pinned the second star on Nicholson during the ceremony attended by Gen. David Petraeus, the top NATO commander in Afghanistan. Nicholson, who has served as a brigade commander in the east and deputy commander for the south, directed the Joint Staff's Pakistan-Afghanistan coordination cell before returning to the country last month.

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Associated Press writers Heidi Vogt in Kandahar and Deb Riechmann and Patrick Quinn in Kabul contributed to this report.