KABUL - The Taliban claimed responsibility for a large suicide car bomb that detonated on Saturday in the heart of the Afghan capital's most secure neighborhood just five days before an election the Islamist group has vowed to disrupt.

 

Afghanistan's Defense Ministry said at least four people were killed and 91 wounded in the blast, which hit outside the sprawling headquarters of the NATO-led international force, near the U.S. embassy, in Kabul.

 

A spokesman for the International Security Assistance Force said there were some ISAF casualties. An official with the Afghan Ministry of Transport, whose headquarters bore the brunt of the blast, said dozens of employees were hurt by flying glass.

 

"Unfortunately, there are casualties," said Canadian Brigadier General Eric Tremblay, an ISAF spokesman. "I am not going to go into numbers. There's Afghan civilians and there are ISAF military."

 

The blast shattered windows in the area and shook buildings in the Wazir Akbar Khan district, home to most major foreign embassies and organizations in the capital.

 

It also rattled confidence in an August 20 presidential election which pits incumbent Hamid Karzai against 35 challengers. Two recent polls have Karzai with a comfortable lead over nearest challenger Abdullah Abdullah, but not enough to avoid a second round run-off.

 

The Taliban, stronger than at any time since they were driven from power eight years ago, have vowed to strike polling stations and threatened reprisals against voters.

 

"The target was the U.S. embassy, but we could not reach it," Taliban spokesman Zabihullah Mujahid told Reuters by telephone from an undisclosed location.

 

BOLD ATTACKS

 

Violence has surged recently, with Taliban fighters staging a handful of bold attacks on provincial government buildings in the south and east, and also launching raids in once-quiet areas in the north and west. Saturday's suicide bomb attack was the first in Kabul since January, when the German embassy was targeted.

 

Taliban fighters also stormed government buildings in the capital on February 11, killing 19 people in an audacious commando-style attack.

Kabul has also recently come under attack by rockets. The vehicle carrying Saturday's bomb appeared to have got through two lightly manned checkpoints before attempting to drive the wrong way through a major reinforced security post, where it was stopped.

 

ISAF's Tremblay said the suicide bomber "entered our defensive system and was blocked by the Afghan army" and then decided to detonate the vehicle. "It was an isolated attack. It's not a complex attack," he said. Abdullah Latif, a driver with the Transport Ministry, said he heard a loud explosion and breaking glass.

 

"People were just arriving at work. There were tens of people injured by the glass," he said. Mohammad Moussa Zaher, a doctor at the Wazir Akbar Khan hospital, told Reuters 55 people had been treated there.

The election is a test for U.S. President Barack Obama's strategy of rushing thousands of extra troops to Afghanistan to tip the balance in an 8-year-old war some in Washington admitted this year they were not winning.

 

Some 30,000 extra U.S. troops have already arrived this year, pushing the total Western force above 100,000 for the first time, including 62,000 Americans. Foreign troop commanders say they will provide perimeter security for the elections, with security at polling stations the responsibility of Afghan forces and police.